Keywords: C Conferences, workshops, and publications etomi pore wirosopy ALD: etomi vyer heposition ANR: egene xtionle de l eherhe CCD: ghrgeEgoupled hevie CVD: ghemil por heposition rnsmission iletron wirosopy TLM: rnsfer vength wethod UV: ltrviolet XAFS: Ery esorption pine truture XANES: Ery esorption xer idge truture XAS: Ery esorption petrosopy XPS: Ey hotoeletron petrosopy XRD: Ery hi'rtion XRF: Ery pluoresene XRR: Ery e)etivity Oxide thin film, Atomic Layer Deposition, Advanced structural characterization, Synchrotron radiation, Synchrotron radiation

pirst of llD s would like to thnk vix winos exEIHEvefESSEHI for (nnil support of my hFhF thesisF ex woon @exEIIExexyHHIRA nd xnosienes poundtion re grtefully knowledgedF s knowledge hF he frros for the engiE neering ssistne of evh retorF e thnk ynhrotron yvisv @ss emE lineA for generl filities pled t our disposlD nd in prtiulrD qF gittoD xF euert nd hF pontineY nd iuropen ynhrotron dition pility @shQ emE lineAD nd in prtiulrD pF grlD hF hufrneD vF ithn nd rF ssernF s knowledge pF honsnti @ihpD spD prneA nd ghF hetvernier @qhent niversityD felgiumA for the time spent nd n greement to eome my reviewersF s thnk eF udrelli @gPP giD vyonAD ghF llee @vwD gie E visD qrenoE leAD hF odriguez @gie E visD qrenoleAD nd hF hF pong @ergonne xtionl vortoryD eA to eome ommittee memers for my hFhF thesis defenseF he nneling experiments were performed in ollortion with eserh inE gineer hF odriguez nd hFhF student wF fertrnd @vetiD tehnology reserh instituteD qrenole @prneAAF wetl ontts were rried out in ollortion with engineer ghF qomez @pstrem ehnologil ltform eD qrenole @prneAAF s thnk F wesot @swiEvergD qrenoleA for the opportunity to perform eleE tril mesurements on REproe rmmtsu sttionD nd F folto @gswiD qe gxD qrenoleD prneA for the opportunity to perform etomi pore wirosope mesurementsF s would like to thnk tFEvF heshnvresD vF penneD gF timenezD wF touvertD F uessdD wFenikinD sF qelrdD rF ousselD wF n wrtin from vortoire des mtériux et du génie physique @qe gxD qrenoleD prneAY iF flnquetD eF grisiD F foihotD hF ininsD F goindeu from swe lortory @qe gxD qrenoleD prneAY hF hF pong from ergonne xtionl vortory @ergonneD eA for invlule help nd dvieF s would like to thnk eF gludel @snstitut xÉivA for our joint experimentsD mster student F tin for his ssistneF s thnk my dvisers rF enevier nd wFEsF ihrd for interesting onverstions nd disussionsD ompetent mngement of my hFhF thesisD nd n exeptionl joint pstimeF pinllyD s thnk my prenh nd ussin friends nd my fmily for emotionl support during this time of my lifeF

Introduction iii

1 ZnO ALD on InGaAs and introduction to the synchrotron studies 1 IFI sntrodution to sn 0.53 q 0.47 es nd ny F F F F F F F F F F F F F F F F P IFIFI snqes ternry lloy for miroeletronis F F F F F F F F F F F P IFIFP snqes surfe preprtion efore ny deposition F F F F F F Q IFIFQ trutureD properties nd pplitions of rystlline ny F F F U IFP ny tomi lyer deposition on sn 0.53 q 0.47 es F F F F F F F F F F F F F W IFPFI etomi lyer deposition proess F F F F F F F F F F F F F F F F F W IFPFP etomi lyer deposition of ny F F F F F F F F F F F F F F F F F IP IFPFQ etomi lyer deposition of oxides on sn 0.53 q 0.47 es F F F F F F IU IFQ ixperiment on synhrotron emlines F F F F F F F F F F F F F F F F F IU IFQFI ss emline @yvisvD intEeuin @prneAA F F F F F F IV IFQFP shQ emline @ipD qrenole @prneAA F

F F F F F F F F F F PH IFR gonlusion F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F PI
2 MOON: An ALD/CVD reactor for in situ studies 23

Introduction ith the ontinued downsling of the trnsistor sizeD the power density dissipted y logi hips inresesD nd this leds to more intensive ooling needF fesidesD the derese of the pplied voltge vlues 'ets the (eld e'et trnsistor @piA swithE ing speed hller IWWUD reyns PHHWF yne of the wys to inrese the swithing speeds of metlEoxideEsemiondutor pi @wypiA is the insertion of sssE mE teril into wypi hnnelD suh s nEsnqesD whih hs higher eletron moility thn i @for instneD µ e is equl to QQHHHD VSHH nd ISHH m 2 F -1 Fs -1 for snesD qes nd iD respetivelyA hel elmo PHIIF he hole moility oth for pEi nd pEsnqes is ove ISHH m 2 F -1 Fs -1 F A prioriD the insertion of n ultr thin oxide is n lterntive solution to lloyed metlEsemiondutor onttsF pirstD the ggresE sive downsling implies tht the thikness of the tive mterils @nE or pEsnqesA is deresed down to few tens of nnometersF et this sleD reting n lloy t the surfe eomes rel hllengeF eondD in the se of snqesD lloying mens the mixing of I or P metl toms with snD q nd es tomsD leding to very omplex phse digrm nd mirostruture with the hope to otin n ohmi onttF he replement of silion @the hnnel mterilA with lyer of higher eletron moilityD suh s sssE mterils nd snqes in prtiulrD is possile solution tht is eing developed in the vex wsxyF hue to the rrier moility enhnement nd gte length slingD the onEstte hnnel resistne of trnsistors is reduedD thus resulting in the domintion of the soureGdrin resistivity to devie performneF henD one of the mjor onerns turns out to e the urrent injetion into the hnnel t the soure nd drin through the metlEsemiondutor onttsF ehieving low metlEtoEsemiondutor ontt resistivity omptile with industril proesses is therefore pressing issue et the metlEsemiondutor onttD the metl permi level n e pinnedD nd s resultD the hottky rrier height preludes low ohmi onttF he insertion of n ultrEthin insultor tunnel lyer in etween the metl nd the snqes hnnel n potentilly redue the ontt resistne egrwl PHIPF elsoD the ultrEthin oxide lyer on the snqes surfe ould e used s n interfil pssivtion lyer @svA for snqes efore the gte insultor dieletri deposition uim PHITD ghen PHIQF sv n suppress dieletri oxide rystlliztion nd n derese lekge urrentF yne of the ndidtes s thin tunnel lyer or sv for snqes is nyF sndeedD the theoretil ny thikness for whih the minimum ontt resistne is hieved is out I nmF he minituriztion of the wypis requires the use of mteril deposition methods tht mke possile to rete ultrEthin lyersF etomi lyer deposition @evhA is hemil vpor deposition tehnique sed on selfElimiting retions ?D this tehnique llows the retion of onformlD homogeneous lyers with thikness Introduction ontrolled t the monolyerF evh hs een widely used proess for the synthesis of thin ny lyer ynell PHIRF roweverD when using evhD one should er in mind tht the growth of mteril t the initil stges n e very di'erent in omprison with the idel stedy growthF hereforeD to rete ultrEthin ny lyers in the nnometer rngeD it is neessry to know preisely how growth ours during the initil stgesF Motivation and targets huring my hh workD s hve pursued two min golsF he (rst one hs een to otin ultrEthin ny lyers on snqes for the potentil use of these lyers s tunnel lyers for metlGnyGsnqes ontts nd s svsF s hve developed proess to otin ultrEthin smooth ny lyers to rete shrp nyGsnqes interfe y tomi lyer deposition tehniqueF he seond gol hs een to visulize the growth of ny on snqes using in situ synhrotron methodsF por tht purposeD s hve een using therml evh retor whih hs een designed for monitoring hemil vpor deposition @ghA nd evh in situ y optil nd synhrotron methodsF en importnt prt of my hFhF work hs een dedited to the retro(tting of the retor for etter ontrol of the evh prmeters nd reproduiility of the proessD s well s to dpt the retor for performing ny evh on snqesF he ojetive ws to use vrious synhrotron tehniques for monitoring ny evh to understnd the growth stges of ny on snqesF pinllyD in view of the widespred interest in zin oxide in our vwq lortoryD the ility to estlish ny growth visuliztion would give the possiilities to study the growth of this mteril on other types of surfeF Organization of the manuscript his mnusript is divided into six hptersF sn ghpter ID we ddress the ny evh growth on snqes nd rie)y outline the two synhrotron emlines ss gitto PHIT @synhrotron yvisvD intEeuin @prneAA nd shQ flmes PHHW @ipD qrenole @prneAAD whih were used for in situ evh experimentsF pirstD we onsider the issue of otining oxides @nd in prtiulr nyA on the snqes surfe nd the potentil pplitions of oxide thin lyers grown on snqesF e remind the rystllogrphi struture of snqes nd nyD the (elds of pplition of these mterilsD nd we detil the snqes surfe preprtion efore growthF henD we give generl desription of the evh tehniqueD nd in prtiulr its pplition to ny evhF sn the lst prt of this hpterD we desrie the two synhrotron emlinesF sn ghpter PD we thoroughly desrie the therml evh retor designed to monE itor growth in situ using synhrotron nd optil methodsF huring my hhD the evh retor ws further ommissioned nd retro(ttedF e dded preursor ypss gs linesD r 2 y evportorD nd the metl preursor uler ws repled y n v evportorF ell these hnges hve llowed performing reproduile evh proessF sn this hpterD we desrie the urrent version of the evh retorD its omponentsD nd operting priniplesF sn onlusion of the hpterD we give n exmple of the ny evh proessD we show how the min prmeters @)owsD tempertures nd pressuresA hnge during the evh proessF sn ghpter QD we present geometri growth model sed on the growth of hemispheroid islnds y evhF e hve developed this model for simulting the sustrteEinhiited growth of type PD ssoited with islnd growthD nd for nlyzE ing our experimentl growth per yle @qgA urvesF xotlyD we hve used the model to reprodue our experimentl qg urves y hnging surfe roughness @or islnd geometri prmetersA during the growthF ghpters R nd S show the results of the ny evh growth on snqes monitored in situ y synhrotron methods t ss @yvisvA nd shQ @ipA emlinesF e used Ery )uoresene @pAD Ery re)etivity @AD Ery sorption speE trosopy @eA nd reiprol spe mps @wA mesurementsF e monitored the thikness of the grown ny lyer y mesuring the re)eted Ery em intensity osilltions during ny evh on @IHHA snqesF e lso olleted tomi fore mirosopy imges tht were used for investigtion of initil stges of ny growthF sn ghpter RD we present the (rst prt of the study of ny growth on snqesD desriing the min results otined during the experiment t the ss emE lineF e desrie in detil the trnsient regime of the ny growthD whih ours t the initil stge efore the stedy @linerA growth regimeF e desrie the fE rition of I nm thik ny lyer deposited on @IHHA snqes surfeD whih ours during the inution period @severl evh ylesAF henD for further ny evh on @IHHA snqesD we demonstrte the pperne of seond regime hrterized y ny islnds growth @sustrteEinhiited growth of type PAF e use our geometri growth modelD presented in ghpter QD for experimentl qg nlysisF he experE iment desried in this hpter ws foused on studying the hnge of struture of the ultrthin @IEP nmA zin oxide lyer using Ery sorption spetrosopyD nd demonstrting the formtion of n ultrEthin lyer t the eginning of growth using tomi fore mirosopy @epwAF sn ghpter SD we foused on studying the hnge of ny struture fter the inution periodF e investigted the e'et of the r 2 yEpreursor )ow vlue on the numer of yles needed for the inution period efore strting the sustrteE inhiited growth of type PF e performed study of the zin oxide struture hnge s funtion of thikness for series of smples with di'erent @IHHA snqes sustrte tempertures during evhF sn the lst ghpter TD we demonstrte one pplition of the ultrEthin ny lyer grown on @IHHA snqesF e show the e'et of the tunnel ny lyer introdued inE etween the metlGsnqes ontt for potentil redution of the ontt resistneF pinllyD s give short synthesis of the prinipl results otined during this work nd s disuss some interesting perspetives for future investigtionsF 2 Chapter 1. ZnO ALD on InGaAs and introduction to the synchrotron studies 1.1 Introduction to In 0.53 Ga 0.47 As and ZnO 1.1.1 InGaAs ternary alloy for microelectronics hile the trnsistor density nd swithing speeds hve inresed exponentilly hller IWWUD ontinued improvements will require greter ooling due to the lrger power densityY ny derese in operting voltge would led to lower swithE ing speeds hel elmo PHIID reyns PHHWD png PHIIF yne potentil solution is the insertion of sssE mterils into the metlEoxideEsemiondutor pi @wyE piA hnnel ldugu PHIPD s they hve higher rrier moilities thn siliE onF e wellEknown ndidte mteril is sn 1-x q x es or snqesD whih hs rrier moility vlue lmost ten times higher thn i onnet PHIID sshii PHHWD kgi PHITD yktyrsky PHIHF he ternry snqes lloy is diret nd gp sssE semiondutorF fy vrying its ompositionD the nd gp n e hnged oolley IWTVD gner IWUH from 0.354 e @snesA to 1.424 e @qesAF purtherE moreD s the snqes nd gp energies orrespond to wvelengths in the nerE infrred @sA spetrumD this mteril n e used to rete s reeivers nd emitters uumr IWWUD rll PHISD ng PHITD highEpower diode lsers hiehl PHHQD devies for highEurrent eletronisD nd mirowve eletronis sed on snqesGsn hetE erostrutures fennett PHHSD ejyn PHISF sn 1-x q x es hs inEflende struture in whih q toms sustitute for the sn tomsF in flende struture @for nyA is shown in (gure IFV@AD for the se of sn 1-x q x esD n toms re repled y sn or q toms in the (gureD nd y toms re repled y es tomsF st ws veri(ed with sn 1-x q x es lloy grown on inEflende sn sustrte y woleulr fem ipitxyD tht the sme lttie prmE eters @ InP aHFSWnmA re otined for sn 0.53 q 0.47 es nd sn @pigF IFI@A dpted from efF sshikw IWWQAF sn this studyD we perform the growth on ommeril pigure IFIX @A he reltion etween diret energy gp nd the lttie onstnt for qD qesD snD nd snes system dpted from efF sshikw IWWQF he lttie prmeters of sn nd sn 1-x q x es ternry lloy for x = 0.53 @sn 0.53 q 0.47 esA re the smeF @A qEesEy nd @A snEesEy ternry ondensed phse digrms from efF rollinger IWWRF sn 0.53 q 0.47 es lyer grown on sn sustrtesF st should e noted tht ntive oxides 1.1. Introduction to In 0.53 Ga 0.47 As and ZnO 3 n form on the sn 0.53 q 0.47 es surfeD whih must e ethed efore the deposition of other mteril on sn 0.53 q 0.47 es surfeF es desried in efF rollinger IWWR some stle ompounds of q 2 y 3 D es 2 y 3 D or es 2 y 5 n form on qes nd snes surfesF he qEesEy nd snEesEy ternry ondensed phse digrms re shown in (gures IFI@A nd IFI@A @from efF rollinger IWWRAF sn the next setionD we desrie the proedure of wet hemil ething of snqes oxidesD snqesD nd snF henD we give desription of the proedure for hemil ething of sustrtes used in this studyF 1.1.2 InGaAs surface preparation before ZnO deposition he sn 0.53 q 0.47 es (001) sustrtes used in this study were provided y qFsFiF sssE v @liseuD prneAF woleulr em epitxy @wfiA ws used to grow PUHEnmE thik lyers of sn 0.53 q 0.47 es on @HHIA sn sustrtesD with IHEnm thik sn u'er lyerF en illustrtion of the smple ross setion is shown in pigure IFPF pigure IFPX hemti of the smple ross setionX ultrEthin ny lyers re deE posited on PUHEnmEthik sn 0.53 q 0.47 es (lm grown y wfi onto QHHEµmEthik sn @HHIA sustrte with IHEnm thik sn u'er lyerF por the hemil ething of oxides formed on the snqes surfeD we hose proedure tht do not eth a priori snqes nd sn mterilsF rerefterD we give (rst desription of the proedure for the hemil ething of snqes oxidesD snqesD nd snF end thenD we desrie the hemil ething proedure whih ws used for the snqes surfe preprtion for the purpose of ny evhF 1.1.2.1 In 0.53 Ga 0.47 As oxides etching yne wy to eth snqes oxides is y rgl id tretment with susequent nnelE ingF un et al. un PHHV used photoEeletron spetrosopy @iA with synhrotron rdition to show tht wet hemil ething of snqes in rgl is e0ient to remove snD q nd es oxidesF he uthors ttempted to remove ll the ntive snqes oxE ides y nneling smples in vacuum t RHH • g for QH minF st is possile to remove es oxides @pigF IFQ@AA fter nneling lthough there re still q nd sn oxides @pigF IFQ@AAF sn ontrst to nneling onlyD uthors show tht it is possile to remove sn nd q oxides y ething the snqes surfe in IH% rgl @≈ 2.9w rglA solution for P minF xo hnge ws oserved for q Qd nd sn Rd peks fter nneling the Chapter 1. ZnO ALD on InGaAs and introduction to the synchrotron studies pigure IFQX @A es Qd nd @A q Qd nd sn Rd i spetr for snqes smpleF fottomX sEreeived smpleY topX nneled t RHH • g for QH min in vacuumF @A hots re the experimentl dt nd the solid lines re the numeril (tting resultsF he four individul omponentsD from left to rightD re q Qd of gllium oxideD q Qd of snqesD sn Rd of indium oxideD nd sn Rd of snqes from efF un PHHVF ethed smples t PHH • g for QH min in vacuum @pigF IFR@AAF es result of the hemil ethingD elementl rseni is produedD whih n e ompletely removed fter nneling @pigF IFR@AAF ome hemil retions ourring on the surfe n pigure IFRX @A es Qd nd @A q Qd nd sn Rd spetr for n snqes smple lened y IH% rgl @≈ 2.9w rglA solutionF fottomX right fter the rgl leningF opX nneled t PHH • g for QH min fter the rgl leningF sn @AD the dots re the experimentl dt nd the solid lines re the numeril (tting results un PHHVF e desried s followsF sn rgl id solutionD ntive rseni oxide eomes rseni idX As 2 O 5 + H 2 O → H 3 AsO 4 , @IFIA thenD the sustrte rets with id to formX AsH 3 : MAs + H + → M 3+ + AsH 3 , @IFPA w = sn or qF ilementl rseni ould e extrted y r 3 esy 4 nd esr 2 hemil retionX 2AsH 3 + 3H 3 AsO 4 ↔ 2As + 3HAsO 2 + 6H 2 O, @IFQA nd AsH 3 + HAsO 2 ↔ 2As + 2H 2 O, @IFRA 1.1.2.2 InP etching huring snqes oxides ethingD it is possile tht sn sustrte n e thinned down s sn is ethed y the sme solutionF o void sn ethingD one needs to selet the orret ething prmetersF xotten et al. xotten IWVR showed tht it possile to eth sn in rgl solutionD utD s expetedD the ething rte strongly depends on id onentrtionF gurve @IA pigure IFSX @A ghemil eth rte s funtion of the rgl onentrtion for pEsn rystlX the rgl onentrtion ws vried y diluting with wter @IA nd onentrted eti id @PAF @EA ghemil ething retions desriing sn ething in rglX @A rEgl nd snE onds replement y snEgl nd Er onds nd @A sngl 3 nd r 3 formtionD dpted from efF xotten IWVRF in pigF IFS@A shows tht when rgl onentrtion is lower thn Sw @16.85% rgl y mssAD there is no sn ethingF roweverD sn hemil ething rte quikly inreses y inresing rgl onentrtionF por instneD the sn ething rte is lredy out 2µm/ min for Vw onentrted rglF gurve @PA in pigF IFS@A demonstrtes liner dependene of sn ething rte in rglXgr 3 gyyr solutionF sn ething in rgl solution ould e desried y the following hemil retionsF he (rst one is synhronous exhnge of ondsF snEgl nd Er onds reple rEgl nd snE onds @pigF IFS@AAF ine the indium nd phosphorus toms t the surfe re triply onded to neighoring tomsD two further onds must e roken in n nlogous mnner to remove eh tom from the lttie @pigF IFS@AAF he hemil produts of tht retion re hydrolyzed sngl 3 nd gs r 3 F guypers et al. guypers PHIR demonstrted tht sn n e ethed in r 2 y 2 Xrgl solutionF he sn ething rte ws out 1.5 nm/ min in r 2 y 2 @HFPSwAXrgl@IwA Chapter 1. ZnO ALD on InGaAs and introduction to the synchrotron studies solutionF n horp et al. vn horp PHIS showed @pigFIFTA tht the sn ething rte strts inresing for rgl onentrtion of out Rw @13.68% rgl y mssAF snstedD snqes is hemilly stle in the sme rgl solutionD t room tempertureF pigure IFTX ithing rte of @IHHAsnesD snqesD qesD nd sn s funtion of rgl onentrtion vn horp PHISF 1.1.2.3 In 0.53 Ga 0.47 As etching eording to 4quide to referenes on sssE semiondutor hemil ething4D snE qes n e ethed from sn surfe y di'erent id solutions glwson PHHIF he surfe roughness degree fter ething is n importnt prmeterF n horp et al. vn horp PHIR showed tht pEtype sn 0.53 q 0.47 es lyers re stle in rglD ut they n e ethed in rglXr 2 y 2 solutionF he snD q nd es ething rte ws monitored y mss spetrometryF efter ethingD the smples re pled in pure wter for 3 min nd then dried y )owing x 2 F pigure IFU@A shows the ething rte of @IHHAsn 0.53 q 0.47 es in rgl for di'erent r 2 y 2 molr onentrtionF snqes surfe hnges fter ething in rglXr 2 y 2 solutionF n horp et al. reported the oservtion of tomi snqes terres with hlf of lttie step height @pigF IFU@AA vn horp PHIQF efter S min ething in 1M HCl : 0.01M H 2 O 2 soluE tionD the roughness inreses from HFIS nm to HFVR nm @see epw imge in pigsF IFU@A nd IFU@AAF o hek tht e'etD we lso performed series of experiments of snqes surfe ething in rglXr 2 y 2 solutionsF e found the onentrtions nd ething time whih llow hnging snqes surfe roughness in the nnometer rnge of HFI nm @see eppendix eAF 1.1.2.4 Etching procedure of InGaAs/InP substrates et lstD for the purpose of growing ny on sn 0.53 q 0.47 es sustrtesD we deided to perform systemtilly the following surfe lening proedureX pigure IFUX @A he ething rte of snqes s funtion of r 2 y 2 onentrtion mesuredfor di'erent rgl onentrtions from efF vn horp PHIRF @A epw imges of n sEreeived @IHHAsnqes wfer nd @A fter ething for S minutes in I w rglGHFHI w r 2 y 2 solution from efF vn horp PHIQF

• the sustrtes were gitted in Rw rgl solution for S min to remove the ntive oxide un PHHVY

• rinsed in deionized wter for QH sY

• nd dried with rgon efore immedite introdution into the evh retorF he smples were then nneled t PHH • g for 30 min in the retor under onstnt )ow of IHH sm nitrogen to evporte es from the surfeF 1.1.3 Structure, properties and applications of crystalline ZnO in oxide @nyA is n ssEs semiondutor with rod energy nd @QFQU eAD whih is thermlly nd mehnilly stle t room tempertureD whih (nds wide pplition in eletronisD optoeletronis nd lser tehnologyF et the present timeD one sueeds in synthesizing ulk rystlline nyD s well s Ph nd Ih nnostruE tures @thin (lmsD plteletsD rodsD wiresD needles etc.AD y mny di'erent growth methodsD inluding vpor deposition uoªodziejzkEdzimsk PHIRF ny is widely used in di'erent res Özgür PHHSF sn ruer industry ny used for reting (llersD tivtors of ruer omponentsF sn phrmeutil nd osmeti industriesD it is used s n dsorer of ultrviolet @A rditionF sn textile industry ny is used s n sorer of lightF sn eletronis nd eletrotehnologyD ny is used for photoeletronisD for reting (eld emittersD sensorsD lsers nd solr ellsF hue to the low toxiity nyD it is lso widely used in the ioindustryF in oxide onsists of two tomsX n nd yD formlly n 2+ nd y 2-F he eleE tron on(gurtion of n tom is 3d 10 4s 2 D nd the eletron on(gurtion of y tom is 2s 2 2p 4 F sn ny rystlD the lttie involves sp 3 hyridiztionF rving ovlent Chapter 1. ZnO ALD on InGaAs and introduction to the synchrotron studies onds formed y sp 3 oritlsD zin oxide lso ehves like n ioni semiondutor @the eletronegtivities of n is IFTS nd of y is QFRRA Özgür PHHSF grystlline ny n hve three types of strutureX ui roksltD hexgonl wurtziteD nd zinElendeF he most stle phse of zin oxide is wurtzite @shown in pigF IFV@AD dpted from efF unigEerez PHITD spe group P 6 3 mcAF n pigure IFVX tik nd ll representtion of ny rystl struturesX @A hexgonl wurtziteD @A ui zin lendeD nd @A ui roksltD w nd re the wurtzite lttie onstnts nd z is the zinElende lttie onstntF @A nd @A re dpted from efF unigEerez PHITD @A from efF Özgür PHHSF tom is surrounded y four y toms whih form tetrhedrl @tetrhedrl siteD h AD lsoD eh y tom sites in the h sitesD it surrounded y four n tomsF he a nd c lttie onstnts rnge from QFPRUSÅ to QFPSHIÅ nd from SFPHRPÅ to SFPHUSÅD respetively Özgür PHHSF he inElende struture @ui systemA for ny n e stilized during growth on ui sustrte @pigF IFV@AD dpted from efF unigEerez PHITAF elsoD t reltively high pressuresD ui rokslt struture for ny n e otined @pigF IFV@AD dpted from efF Özgür PHHSAF xon intentionlly doped ny exhiits properties of n nEtype semiondutor with very high eletron densities of out IH 21 m -3 Özgür PHHS @for instneD it is shown for ny deposited y dio prequeny wgnetron puttering winmi IWVSAF xturl ny defetsD suh s oxygen vniesD re the use of nEtype ondutivity of undoped nyF hoping of nyD nEtype ondutivity n e esily otinedD ut otining pEtype ondutivity is still prolem due to the in)uene of ny internl defetsF he growth of the Ph ny lyer n e rried out y vrious methodsD suh s wetlorgni hemil vpor deposition @wyghAD woleulr em epitxy @wfiAD ulsed lser deposition @vhAD putteringD nd etomi lyer deposition @evhA ärkijärvi PHIRF he growth nd orienttion of zin oxide on the sustrte surfe depend on the type of sustrteD the growth tempertureD nd other physiE ohemil prmetersF por ny lyersD preferred rystllogrphi diretions of growth re usully oE servedF por instneD for ny lyers grown y evhD t deposition tempertures elow UH • g the ny exhiits preferred orienttion long 002 diretionD ove UH • 1.2. ZnO atomic layer deposition on In 0.53 Ga 0.47 As 9 nd until ITHEPHH • g the preferred growth ours long 100 diretionD for ITHEPHH • g temperture rnge the grins re mostly oriented long Exis perpendiulr to the sustrteD nd for deposition tempertures ove PPH • gD the growth swithes gin to the 002 diretion ynell PHIRF en exmple of @IHHA ny wurtzite growth surfe is shown in pigF IFW@A dpted from efF ous( PHHHF elsoD depending pigure IFWX @A urfe struture nd ross setion of ny @IHHA surfes dpted from efF ous( PHHH nd @A yEpolrD @A nEpolr Exis diretions in the ny wurtzite ell dpted from efF quillemin PHIUF on the sustrte surfeD the growth of oth Ph nd Qh ny n ours long nE or yEpolr Exis diretions @i.e. the nEy ond long the Exis is prllel or ntiE prllel to the sustrte surfe normlD see pigF IFW@A nd IFW@A dpted from efF quillemin PHIUAF 1.2 ZnO atomic layer deposition on In 0.53 Ga 0.47 As 1.2.1 Atomic layer deposition process he sling down eletronis mkes it neessry to ontrol the thikness of the lyers of mterils t the tomi level nd to rete ultrEthin lyers hller IWWUF yne importnt tehnique for depositing thin (lms with good thikness ontrol for vriety of pplitions is etomi vyer heposition @evhAF evh is hemil vpor deposition @ghA tehnique nd it is sed on selfElimiting hemil retion of regents present in the gs phse with smple surfe qeorge PHHWF evh is widely used for the retion of displysD integrted iruitsD hrd dis drivesD photovolti nd optil omponentsD nd for funtionl nd protetive otE ing of elements kkl PHIHD veskelä PHHQF he evh method llows the retion of wide rnge of mterilsF woreoverD evh llows the retion of ultrthinD denseD nd smooth (lms kkl PHIHF he method hs dvntges over other deposition tehniquesD for instneD gh nd plsm vpor deposition @hA methods do not lwys llow to otin the sme level of uniformityD onformlityD nd thikness ontrolF he min di'erene of evh from gh is tht in the se of ghD gs regents e nd f re present ontinuously in the retor hmerD insted in the se of evhD the pulses of regents e nd f re seprted y inert gs pulses nd retor hmer purgeF husD in the se Chapter 1. ZnO ALD on InGaAs and introduction to the synchrotron studies of ghD the two regents present in the retor hmer use ontinuous mteril depositionD insted of the se of evhD the mteril deposition ours in suessive steps @repeted ylesAF por this resonD the evh hs the ility to ontrol the deposited mteril thikness t sunnometer rngeF sn the idel onditionD one n reh lyerEyElyer deposition ontrolF e generl desription of the evh proess is shown in (gure IFIH @from efF tohnson PHIRAF he evh proess inludes repeted ylesF yne evh yle inE pigure IFIHX hemti of evh proess from efF tohnson PHIRF @A ustrte surfe hs nturl funtionliztion or is treted to funtionlize the surfeF @A reursor e is pulsed nd retswith surfeF @A ixess preursor nd retion yEproduts re purged with inert rrier gsF @dA reursor f is pulsed nd rets with surfeF @eA ixess ofpreursors nd retion yEproduts re purged out with inert rrier gsF @fA teps @EeA re repeted until the desired mteril thikness is hievedF volves stges of gsEsurfe 4hlfEretions4F o rete twoEomponent mterilsD two hemil regents @preursorsA in the gs phse re used during n evh yE leF he sustrte pled in the retor hmer must hve hemilly retive surfe for retion with one preursor @AF e su0ient mount of preursor e is injeted into the retor hmer during su0ient time for otining full selfE limiting retion of the e preursor with the tive surfe sttes of the smple @(rst hlfEretionA @AF oD idellyD no more thn one monolyer of regent remins on the smple surfeF sn the next stepD the retor hmer is purged with n inert gs @suh s x 2 or erA to ompletely evute the retion produts from the retor hmer @AF efter purgingD the preursor f is injeted nd it rets with the smple surfe @seond hlfEretionA leving one monolyer @dAF henD ginD the retor hmer is purged with n inert gs to evute preursor f retion produts @eAF ell the @A to @eA stges form one evh yleF he numer of evh yE les is repeted @fA until the required thikness of the mteril is rehedF his kind of selfElimited gsEsurfe retions llows to ontrol the thikness of the mteril lyerEyElyer nd to rete ultrthin lyersF et presentD wide rnge of synthesized preursor moleules mkes it possile to rete lrge numer of mterils y evhF he elements of whih some mterils hve een grown y evhX oxidesD nitridesD sulphidesD selenidesD telluridesD pure elementsD nd other wiikkulinen PHIQF sn the periodi tle of elements shown in (gure IFIID some of the ompounds tht n e synthesized y evh proess re listedF pigure IFIIX yverview of the mterils grown y evh from efF wiikkulinen PHIQF qrowth of pure elements s well s ompounds with oxygenD nitrogenD sulfurD seleniumD telluriumD nd other ompounds grouped together re indited y shdings of di'erent typesF he evh proess n e di'erent for reting di'erent mterilsF sn the se of soElled therml evhD the preursor rets with the smple surfeD while the smple temperture is mintined t onstnt vlueF roweverD plsm or rdilE enhned evh n e usedD s for instneD for depositing montomi mterils ro(jt PHIIF por exmpleD hydrogen plsm is used to rete hydrogen rdils in the gs phse to redue the metl or semiondutor preursorsF rydrogen rdils n lso e produed using hot tungsten (lmentF sn ddition to singleEelement mterilsD using plsmEenhned evhD it is possile to deposit ompound mterils t muh lower tempertures thn therml evhD due to highD diverseD ut seletive retivity delivered y plsm to surfe without hetF ypil sustrte tempertures for the evh proess rnge from room temperE ture to SHH • gF por most mterilsD there is rnge of tempertures @evh windowA in whih selfElimiting hemil retions our nd one monolyer of preursor ovE ers the smple surfe during hlfEretionF pigure IFIP shows the growth per yle versus the sustrte temperture from efF qeorge PHHWF sn the evh window temE perture rngeD the growth per yle @qgA is onstntD ut for lower nd higher Chapter 1. ZnO ALD on InGaAs and introduction to the synchrotron studies pigure IFIPX hemti of possile ehvior for the evh growth per yle @qgA versus temperture showing the evh window from efF qeorge PHHWF temperturesD qg n e oth higher or lower thn the qg vlue in the evh window s shown in (gure IFIPF por lower tempertures thn those of the evh windowD the preursors ondense on the smple surfeD then higher qg vlue is oserved thn the qg vlues in the evh windowF roweverD for the sme temE pertureD if therml energy is not su0ient to hieve the hemil retion of the preursors with the smple surfeD then lower qg vlue is oserved in omprE ison with qg in evh windowF por higher tempertures thn those in the evh windowD the preursor n desor from the smple surfe due to the high therml energyD then lower qg vlue is oserved thn the qg vlue in evh windowF roweverD for these temperturesD therml energy n e high enough to deompose the preursors nd strt dditionl retions on the smple surfe @this ehvior is similr to ghAD then higher qg is oserved in omprison with qg in evh windowF ell retions with onstnt temperture nd onstnt growth per yle re deE sried ove for the se of stedy stte of growth when the qg is onstnt from one yle to nother nd the mehnism of hemil retions is the sme for every yleF roweverD evh on the initil stges @for the (rst ylesA my e di'erE ent from further evhF por exmpleD for some mterilsD quite long time to strt the nuletion on the sustrte surfe is needed qreen PHHPF husD the study of the initil stges of evh for the retion of ultrthin lyers is of prtiulr interest ilm PHHID qrus PHHRD ehrist PHHSD ind PHHWF he initil stges of evh re disussed in more detil in hpter RF 1.2.2 Atomic layer deposition of ZnO ny evh method is widely used in the retion of thin (lm trnsistorsD solr ellsD lightEemitting diodesD gs sensorsD nnostruturesD nd other devies for miroE nd nnoeletronis ynell PHIRF he evh method mkes possile ny deposition over wide rnge of temperturesD depending on the seleted preursorsD rnging from room temperture quziewiz PHHV to high tempertures @for instneD THH • g en PHHWAF his is n dvntge for reting eletronis deviesD euse it is neE essry to use rther low temperturesD usully lower thn RHH • gD in the prodution proessF he deposition temperture in evh window depends on the physiohemE il proesses on the smple surfe ourring during the retion with preursorsF wo preursors re used for ny evhX metl preursor ontining zin tomD nd n oxidnt moleule ontining oxygen tomF he nEpreursor nd yEpreursor @oxidntA ret with smple surfe during the (rst nd seond hlfEretionsD respeE tivelyF he (rst nEpreursor tht ws used for the ny evh ws n@gr 3 gyyA 2 or zin ette @neA @in omintion with wter s yEpreursorA mmenm IWVSF roweverD sustrte temperture for ny evh using ne nd wter is round PVH • gD i.e. rther high tempertureF et presentD for ny evhD the most used nEpreursor is n@g 2 r 5 A 2 or diethylzE in @hinA in omintion with wter s yEpreursorF elsoD n@gr 3 A 2 or dimethylzE in @hwnA n e used s nEpreursorF sing hwn or hin in omintion with wterD it is possile to otin the sme deposited mteril qulityD lthoughD in se of using hwnD the growth rte is slightly higherD thn in the se when hin used @igger moleulesD steri hindrne e'et is higherA nsknen PHIIF relyD elementl n nd ngl 2 re used s preursorsD requiring higher deposition tempertures of out RVHESHH • g uoplko PHHSF he most ommon yEpreursor for ny evh is r 2 yF ythersD like y 2 Dy 3 D x 2 y gsesD nd y 2 nd r 2 y plsm hve een used s yEpreursors too ynell PHIRF he hoie of the yEpreursor lso 'ets the prmeters used during the ny evh proessX the sustrte temperture @the evh window is di'erent for di'erent preursorsAD the pulse time of the preursorsD nd the vlue of the preursor )ow during its injetion into the retor hmerF sn hpter PD we desrie n evh retorD whih uses hin nd r 2 yD nd hin nd x 2 y preursors for ny deE positionF husD here we desrie the possile hemil retions ourring on the smple surfe during evh when these ouples of preursors re usedF he (rst hlfEretion ourring on the smple surfeD when hin nd x 2 y preursors re usedD n e represented s follows vin PHHWD vu IWWUX

|| -y + n(g 2 r 5 ) 2 -→ || -y -n(g 2 r 5 ) + (g 2 r 5 ) rdil (g 2 r 5 ) rdil + (g 2 r 5 ) rdil -→ (g 4 r 10 ) utne @IFSA
he uthors suggest thtD g 2 r 5 -n ond in n@g 2 r 5 A 2 moleule is thermlly rkedD nd @g 2 r 5 A-n • rdils dsor on the yEterminted smple surfeF @g 2 r 5 A n ret to stle utne moleules @g 4 r 10 AF henD when x 2 y is injetedD the seond hlf retion n e written sX x 2 y -→ x 2 + y rdil y rdil + ny surfe @nEtermintedA -→ yXny surfe @IFTA he uthors elieve tht oxygen rdils re generted through therml rking of x-y onds in x 2 y moleulesF henD yErdils dsor on nEterminted surfeF he evh window for hin nd x 2 y preursor omintion ws found etween PWHEQIH • gF he uthors oserved derese of qg for tempertures elow PWH • gF Chapter 1. ZnO ALD on InGaAs and introduction to the synchrotron studies hey ssoited it with insu0ient therml energy for rking y-x ond in x 2 y moleulesF por tempertures higher thn QIH • gD more hin moleules re totlly deomposed nd dsored in ddition to one monolyerD this leds to n inrese of the qgF sn the following hptersD we demonstrte ny evh using hin nd r 2 y preursorsF e lso used moist ir insted of wterD elieving tht r 2 y moleules re the min omponent ting s n yEpreursorF e onsider more in detil the desription of physiohemil retions ourring on the smple surfe during hin nd r 2 y pulsesF huring the nEpreursor pulseD the hin moleules ret with the yrEterminted smple surfeD this retion n e desried sX

|| -yr + n(g 2 r 5 ) 2 -→ || -y -n(g 2 r 5 ) + g 2 r 6
@IFUA hin moleule dsors to the yrEterminted surfe nd loses one @g 2 r 5 A ligndF henD the pulse of the oxidnt is followed y seond hlfEretionX

|| -y -n(g 2 r 5 ) + r 2 y -→ || -y -nyr + g 2 r 6 @IFVA
huring this retionD the smple surfe eomes yrEtermintedF elsoD monoethyl zin n ret with the yr groupD produing n on the surfeX

|| -y -n(g 2 r 5 ) + (|| -yr) -→ (|| -y) 2 -n + g 2 r 6 @IFWA
qo et al. qo PHIT demonstrted model in whihD fter retion of yr group with hinD oth monoethyl zin nd re zin my remin on the smple surfe @see equtions IFU nd IFWAF pigure IFIQ shows the results of these two retionsF huring retion desried y eqution IFU @pigF IFIQ@AA the moleule of pigure IFIQX edsorption of hi on yrEterminted surfe @hydroxyltedA in @A stnding on(gurtion nd @A sitting on(gurtionF he dotted ox refer to nE polr ny surfe @efore hydroxyltionAD from efF qo PHITF @A everge gw pulse shpes for ny evh from efF ilm PHHQF ∆w A is the mss hnge fter hin pulseD ∆w A + ∆w B is the totl mss hnge fter r 2 y pulseF diethylzin rets with the yrEterminted surfe nd s result the n tom onds 1.2. ZnO atomic layer deposition on In 0.53 Ga 0.47 As 15 to one y tom nd one ethyl g 2 r 5 @4stnding on(gurtion4AF sf hin moleule ollpses on the neighoring Eyr hemil site @or prolyD hin moleule rets with two yrEgroupsAD retion following eqution IFW @pigF IFIQ@AAD uthors ll it 4sitting on(gurtion4F efter hin pulseD if the smple surfe is @g 2 r 5 AEterminted @stnding onE (gurtionAD then during wter pulseD the hevy g 2 r 5 rdil is repled y light Eyr group @eqution IFVAF husD in this seD the totl mss of the mteril should dereseF roweverD some in situ qurtz rystl mirolne @gwA mesurements during ny evh showed tht the hnge in mss during the wter pulse n e posE itive ous( PHHHD ilm PHHQF es n exmpleD pigure IFIQ@A shows in situ gw mesurements for one ny evh yle ilm PHHQF yne oserves tht the totl mss inreses oth during the pulse of hin @∆M A in the (gure IFIQ@AA nd durE ing the pulse of r 2 y @∆M B in the (gure IFIQ@AAF henD one possile explntion of the positive mss hnge is tht the retion desried y the sitting on(gurtion @eqution IFWA hs hppenedD during the susequent wter pulse the re n toms dsor r 2 y moleulesD nd this ompenstes the mss loss due to the retion of wter moleules with @g 2 r 5 AEterminted surfe @eqution IFUAF ekmn et al. ekmn PHIV report lulted growth per yle @qgA vlE ues s funtion of the sustrte temperture @pigF IFIRA otined y density funtionl theory @hpA simultion of di'erent hemil retions ourring on the smple surfeD using hin nd r 2 y preursorsF pigure IFIR shows tht in the pigure IFIRX he growth per yle @qgA s funtion of temperture from efF ekmn PHIVF hi'erent symols @empty squresD empty irlesD lk irlesA orrespond to di'erent experimentl runsF he viI nd viP orrespond to the hin nd monoethyl zin @winA ligndEexhnge retions on the surfe leding to win nd nD respetivelyF gse I nd se P re the low nd high temperture ethylEsturted struturesD respetivelyF lowEtemperture rnge @QHEIHH • gAD the qg is low ompred to higher temperE turesD uthors explin this y the ft tht the kineti rrier for the removl of g 2 r 5 lignds is not high enough due to the low sustrte tempertureF he E tivtion energy for lignd exhnge retion etween dsored hin nd surfe Chapter 1. ZnO ALD on InGaAs and introduction to the synchrotron studies yrEgroupGr 2 moleule ws tken in the rnge of HFPQ E HFRU e @this retion is deE noted s viIAF es the sustrte temperture inreses @to IHHEIRH • gAD the numer of viI retions inresesD whih leds to n inrese of qgF por IRHEIVH • g temE perturesD it eomes possile to remove the seond g 2 r 5 lignds from n ound to the smple surfeF he tivtion energy used in the hp lultions for the removl of the g 2 r 5 lignd from monoethyl zin ws tken in the rnge of IFQI E IFSP e @this retion is denoted s viPAF por higher tempertures @>IQH • gAD for hp lultionsD it ws simulted surfe inluding the retions desried y the eqution IFW @lk irles on pigF IFIRAF por tempertures >IVH • gD derese of qg ws oservedD minly due to the desorption of hin preursorF sing in situ pourier trnsform infrred @psA spetrosopyD it ws shown wkus PHIU tht t temperture of ISH • gD IT% of the g 2 r 5 lignds remins on the surfe during r 2 y pulseD only rising the temperture to PHH • g n remove ll the g 2 r 5 lignds from the surfeF he (gures IFIS@A quziewiz PHHV nd IFIS@A qo PHIT show the experimenE tl qgs s funtions of temperture in the se when hin nd r 2 y preursors re usedF yne oserves tht the temperture of the evh window is in the rnge from pigure IFISX he ny growth rte versus growth temperture when hin nd wter re used s preursors for the evh proess @A from efF quziewiz PHHVF he ny (lms were PHH nm thik nd deposited on i sustrte @A from efF qo PHITF he growth rte is mesured y spetrosopi ellipsometryF IHH • g to PHH • g nd the qg vlues in tht window re pproximtely 0.16E0.21 nmFy -1 F xote tht there exists nother reson for the qg to inreseX the preursor moleules in exess @i.e. there re more moleules thn needed for one monolyer overgeA re not evuted during the purge of the retorD then the mteril growth ours in gh modeD whih results in higher qg vluesF 1.2.3 Atomic layer deposition of oxides on In 0.53 Ga 0.47 As he use of snqes s the hnnel mteril neessittes growth of suitle oxideD s for instne those tht n e employed s the gte dieletri while minimizing issues due to permi level pinning egrwl PHIP suh s lrge ontt resistneF wny di'erent gte oxide lyers hve lredy een grown on snqesEhnnel wypis lle PHHW y evhX el 2 y 3 e PHHRD un PHHUD ry 2 rung PHHWD rfely un PHHUD vely 3 eguirreEostdo PHHVD nd rfy 2 gho PHHRF etomi lyer deposition of el 2 y 3 even indues selfElening nd removl of nturl nd unE ontrolled oxides on the snqes surfe rk PHIUF hile el 2 y 3 is one of the est ndidtes for snqes surfe pssivtionD nother thin lyer etween it nd snqes @i.e.D n interfil pssivtion lyer or svA tht n suppress dieletri oxE ide rystlliztion nd derese lekge urrent nd interfe stte density is highly desirleF ythers hve found tht evhEgrown svs of qd 2 y 3 nd 2 y 3 n led to higher dieletri onstnts thn el 2 y 3 lone emeen PHIRD nd HFREnmEthik sv of v 2 y 3 promotes smller hysteresis nd lower gte lekge ghng PHISF e thin lyer of el 2 y 3 ws used s n sv in rfiyGel 2 y 3 Gsnqes gte stk to reE due the interfe stte density nd void permi level pinning t the rfiyGsnqes interfe re PHIRF rereD we investigte the growth of ny svs uim PHITD ghen PHIQ y evh on snqes ghen PHIQD whih hs lredy een shown to redue the formtion of oth q nd es oxides nd unpin the permi level in snqesEsed wypis vio PHIQD vio PHISF sn the study of low resistivity metlEinsultorEsemiondutorsD it hs lso een demonstrted tht ny n t s good tunnel rrier on snqes egrwl PHIPF he uthors lulted tht the minimum spei( ontt resistivE ity for the elGnyGsnqes system requires ny insultor thikness of only HFT nmF 1.3 Experiment on synchrotron beamlines ine the pioneer work of pong et lF pong PHIH t ergonne xtionl vorE toryD severl groupsD inluding oursD hve uilt dedited setups for using Ery light to study evh growth operando hendooven PHITF yver the pst dedeD in situ hrteriztion during evh hs een instrumentl towrds hieving funE dmentl understnding of evh surfe hemistryF e gret del of lortory in situ studies is rried with qurtz rystl mirolne @gwAD mss spetromeE tryD nd optil hrteriztion tehniques vngereis PHHWD lthough they re not spei(lly surfe sensitiveF fesidesD it is not so esy to integrte evh into seE tups for surfe spetrosopy or mirosopy tht often require ultrEhigh vuum opertionF elthough reent results were reported from ner mient pressure unudsen PHITD red PHISD these surfe siene tehniques re most widely impleE mented in vacuum nd the smple is mesured fter trnsfer from the evh retor to dedited in vacuum hmerF por the purpose of the present work we hve used ustomEuilt portle retorD whih ws funded y the prenh ex @xoF Chapter 1. ZnO ALD on InGaAs and introduction to the synchrotron studies exEIIExexyEHHIRA nd the xnosienes foundtion @hr hillon pong9s hir of exelleneAF st llows to use omplementry suite of in situ synhrotron Ery tehniques @re)etivityD grzingEinidene )uoreseneD di'rtionD sorptionY see hpter PAF he high rilline t third genertion synhrotron llows the sensitivity for studying ultrEthin (lms nd nnostruturesF he ility to tune the Ery em energy nd ontrol the photon polriztion opens up the possiility for ene(ting synhrotron Ery methods for studying thin (lms tht nnot e used in the home lortoryD s for instne grzingEinidene )uoreseneD Ery nomlous di'rE tion @wehAD Ery sorption @epAF wonitoring in situ ny tomi lyer deposition y synhrotron tehniques @reE sults re desried in the following hptersA ws rried out in synhrotron enE ters on two emlinesX ss @yvisvD intEeuin @prneAA nd shQ @ipD qrenole @prneAAF he evh retor reted for the in situ experiment @the deE sription of the retor nd the operting priniples re explined in the next hpE terA ws moved nd implemented onto hevyEduty di'rtometer t the emlinesF sn this setionD we present rie)y the two emlines ss gitto PHIT nd shQ flmes PHHW nd emphsize their unique nd omplementry pilities for rE rying in situ studies during growthF 1.3.1 SIRIUS beamline (SOLEIL, Saint-Aubin (France)) ss is new emline t yvisv synhrotron @intEeuinD prneAF his emline ws designed for studying thin (lmsD nnostruturesD nd dvned mteE rils oth ex situ nd in situ Ery studiesF he min fetures of ss emline re the presene of fst nd very sensitive monohromtor @the energy of the E ry em n e hnged from tender to the hrd EryA nd the ility to swith the ontrolled polriztion of EryF eville energy rnge from IFR ke to IP ke overs most of the sorption edges of elements in semiondutors nd funtionl oxidesF pigure IFIT shows the optil elements of ss emline gitto PHITF pigure IFITX impli(ed lyout of the ss emline with the optil elements represented from efF gitto PHITF he undultor epple ss eQT produes photons in the rnge of IFREIP ke with vrile polristionF hen two monohromtors re instlledF he (rst one is doule rystl mounted with @IIIAi rystls for energies in the rnge from P to IP keD the seond pir of @IIIAsn rystls for energies in the rnge from IFU to R keF hen @IIIAi rystls re usedD the energy resolution ∆i/i is IH -4 D the photon )ux on the smple is IH 13 photons/s in the PES ke energy rnge nd dereses to 3×10 12 photons/s t IH keF he seond one is multilyer grting monohromtor whih llows the ess to lower energy @down to IFR keA nd n preserve irulr polristionF he monohromtor is followed downstrem y four mirrorsF he (rst one ounes down the emD hieving hrmonis rejetionF he seond nd the third mirrors re for vertil nd horizontl em fousingF he fourth mirror is used to set the inidene ngle when the smple surfe is horizontlF he evh retor wyyxD desried in the next hpter PD is mounted on hevy sixExis tower of the ss di'rtometer @see pigF IFIUAF his tower llows pigure IFIUX he UEirle di'rtometer in the tower on(gurtion with the wyyx retor mounted onD severl detetors used for di'erent tehniques from efF gitto PHITF moving the smple ording to six degrees of freedomX vertil trnsltions @the trvel rnge is PHH mmD resolution is ±HFI µmAD xEy horizontl trnsltions @SH mmD ±IH µmAD full vertil xis rottion heth @QTH • D ±HFHHHP • AD nd two rossed tilts 20 Chapter 1. ZnO ALD on InGaAs and introduction to the synchrotron studies elphx nd elphy @±IH • D ±HFHHHP • AF es shown in (gure IFIUD severl detetors n e mountedX Ph eh QFP detetor for Ery di'rtion @hA re)etivity @AD nomlous di'rtion @weh nd hepAY Ph sve I w detetor for grzingEinidene smllEngle xEry sttering @qseAD nd four element ggh fruker pvsh qe SHRH )uoresene detetor for Ery )uoresene @pA nd Ery sorption spetrosopy @eAF p nd qse n e mesured in prllelD nd for instneD nd h n e performed one fter the otherF 1.3.2 ID3 beamline (ESRF, Grenoble (France))

gomplementry in situ experiment minly foused on di'rtion ws rried out on the shQ emlineF shQ is surfe di'rtion emline t iuropen ynhrotron dition pility @ipA in qrenole @prneAF he shemti imge of the optil elements of shQ emline nd the hrteristi distnes etween them re shown in (gure IFIVF hownstrem to the optis huthD there re two experimentl huthesF pigure IFIVX e shemti view of the optil elements t the shHQ emlineF he em goes from right to left stemming from the undultorsF he optil elements on the em pth re @iA in the optis huthX hnnel ut monohromtorD ylindril endle mirrorD seond mirrorD @iiA in the (rst experimentl huthX vertil fousing uirkEfez @ufA mirrorD horizontl fousing uf mirrorD smpleD @iiiA in the seond experimentl huthX vertil fousing uf mirrorD horizontl fousing uf mirrorD smpleF he numers elow the grph re the distne to the undultors @middle of the stright setionA from efF flmes PHHWF hree undultors provide uniform photon )ux in the TEPS ke energy rngeF e monohromtor @two i @IIIA rystlsA is followed y ylindril endle mirror whih provides vertil nd horizontl fousing of the em @ typil size is 30 × 40 µm 2 A yptis provides monohromti Ery em on the smple with )ux 2×10 13 photons/s within the whole energy rngeF por the purpose of our experimentsD we did not use the uf mirrorsF 1.4. Conclusion

21

he evh retor wyyxD ws mounted on zExis vertil di'rtometer @in the experimentl huth irIAD espeilly suited for smples with horizontl surfe geometryF e Ph wxipix T M pixel detetor ws used for D h nd reiprol spe mps mesurementsF e )uoresene detetor ws instlled to perform p nd e experimentsF end Ph sve detetor ws used for reording qse imgesF yne very useful feture of emline shQ is the possiility to perform 4zpE sns4D tht is to move ontinuously one di'rtometer motor while ounting the sttered photonsF hisD omined with the high photon )ux delivered y the soureD gives the possiility to mesure lrge in plne reiprol spe mps in very short period of time @severl order of mgnitudeA in omprison to the lssi stepEyEstep quisition mode oool PHISF his feture is of gret interest for in situ studiesF e used it for following the trnsition from morphous to rystlline @wurtziteA ny s it is demonstrted in ghpter SF

Conclusion

e hve rie)y desried the struture nd properties of nyD s well s the sn 0.53 q 0.47 esGsn sustrtesF etomi lyer deposition is one of the most suitE le methods for reting ny ultrEthin lyers on sn 0.53 q 0.47 es sine evh mkes possile to ontrol the thikness of the deposited lyers t the ngstrom rngeD nd the deposition temperture n e in the wide rnge of low tempertures @from room temperture up to SHH • gAF ny ultrthin lyers on snqes n e used s n interfil pssivtion lyer @svA nd tunnel lyers for permi level depinning in metlGsn 0.53 q 0.47 es onttsF e hve lso shown the vrition of key prmeE ters of evh proessD suh s sustrte tempertureD preursor )ow nd pulse time ontrol ny growthF o rete ultrEthin ny lyersD it is neessry to know how the growth vries y vrying the key prmeters of the evh proessD nd how ny growth ours in the initil stgesF In situ monitoring of ny evh on snqes using synhrotron methods provides informtion on the hemil nd struturl prmeters of the deposited ny lyers for every evh yle oth t the initil stges nd in the stedy regime of growthF he experiments were rried out on ss emline @yvisvD intEeuin @prneA nd shQ emline @ipD qrenole @prneAA whih llowed us monitoring ny evh y using minly pD Ery di'rtion nd Ery sorptionF Chapter 2 MOON: An ALD/CVD reactor for in situ studies

In this chapter, we describe in details the atomic layer deposition (ALD) reactor hereafter called "MOON". The MOON reactor has been designed and built for monitoring in situ ALD experiment during growth. The ALD process is known as a method allowing to create thin, homogeneous and conformal layers for micro-and nanoelectronics at low temperatures. The problematic of material growth in the early stages of ALD has become an important issue for the growth of ultra-thin layers. With the MOON reactor, the growth of materials at the initial stages can be studied in situ by various optical and X-ray methods during ALD. The MOON reactor, developed at the LMGP laboratory in cooperation with other laboratories, can be moved to dierent synchrotron centers to perform ALD process monitored by X-ray synchrotron methods. In the same way, some optical methods can be applied both at the LMGP laboratory and at the synchrotron centers. An important part of my PhD work has been devoted to the retrotting and commissioning of the MOON reactor and process development for obtaining very reproducible ALD cycles and growth conditions. During the retrotting of the reactor, we developed a metal precursor evaporator system that allows injecting pure wellcontrolled gas metal precursor ow into the reactor chamber. We also installed bypass gas lines that allow stabilizing the ow and pressure values of the gases before their injection into the reactor. Also, a water evaporator was installed and tested in addition to the existing nitrous oxide precursor injection system.

First, I give a general description of the MOON reactor, and a brief description of the methods that can be used to study the growth of the ALD material. Then, I describe in details the components of the ALD reactor and demonstrate how the main parameters change during ALD process. At the end, I give an example of reactor operation during ALD. The whole ALD process of the MOON reactor is automated and a high reproducibility of the main parameters of ows, pressures, and temperatures is achieved. The main results obtained by in situ measurements during ALD process are explained in the next chapters. 2.1 Introduction etion mehnism of evh proesses n e studied in situ y using di'erent tehniques unps PHIQD s for instneX mss spetrometryD qurtz mirolE neD infrred spetrometryD surfe photosorptionD inrementl dieletri re)eE tionD surfe photointerfereneD re)etne di'erene spetrosopyD optil emission spetrometryD nd spetrosopi ellipsometryF hese methods provide informtion out retion mehnisms nd surfe hemistryD the optil prmeters of the mterilD the thikness of the deposited lyerD nd the mount of deposited mteE rilF hey re onvenient to use in the lortoryD ut thenD evh retor hs to e designed in speil wys nd sometimes equipped with spei( windows for eing le to rry out in situ experimentsF he wvelength of hrteriztion tools n e sled down to the Ery wveE length if synhrotron rdition nd tehniques re usedF ynhrotron tehniques llow monitoring hnges t the nnometer sle due to high Ery em rillineF he energy of the Ery em n e seletedD whih gives gret opportunity for pplying vriety of methods for reserhF ynhrotronEsed tehniquesD tht re ommonly used to monitor in situ tomi lyer depositionD n e divided in severl groups ording to their pilities to proe struturl or hemil properties t di'erent sles hevlooEgsier PHIRX Ery re)etivity @AD grzing inidene smll ngle sttering @qseAD grzing inidene Ery hi'rtion @hAD Ery )uoresene nd Ery spetrosopyF ome of the tehniques require speil deE sign of the evh retorF llows monitoring the thikness nd density of the deposited mteril s well s the surfe nd interfe roughnessesD in situ during evhF qse llows studying morphology nd roughness of evh mterilD s for instne islnd shpeD size distriution nd fetsD s well s the verge distne inEetween islndsF st is widely used tehnique for nnosle ojet hrterizE tion enud PHHWF hen qse is usedD evh retor must e equipped with trnsprent nd low Ery sttering windows @ommonly used re feD upton nd iiu windowsA s well s emEstops nd slits @or ldesAD )ying tue in etween the smple nd the PhEdetetorD to derese s muh s possile ll soures of prE siti stteringF elsoD the evh retor must hve the possiility to rotte the smple round n xis perpendiulr to its surfeF Ey pluoresene @pA mesurements re used for elementl nlysisF In situ p during evhD whih llows to monitor very smll mount of mteril from the very (rst evh ylesD is n idel tool for studying the nuletion stgeF Ey esorption pine truture @exi nd ixtended epA spetrosopyD owing to its tomi nd eletroni shell seletivityD gives informtion out the vlene nd lol tomi environment of the soring toms s well s on the empty stte density ove the permi levelF por pEsed tehniquesD high signlEtoEnoise is requiredD this mens hving the possiility to minimize the elsti sttering nd optimize the p detetor solid ngleF Ey hotoeletron petrosopy @A is surfe sensitive tehniqueD tht is used for hemil @vlene sttesA nlysisF o study omposition nd hemil elements in evhEgrown mteril y D n ultrEhigh vuum is neessry llrid PHIPD llrid PHHVF everl groups hve lredy designed di'erent evh retors for in situ experiE ment using synhrotronEsed tehniques llrid PHHVD pong PHIHD hendooven PHIID hevlooEgsier PHIID uolnek PHIID llrid PHIPD qeyer PHIPD qeyer PHIRD ulug PHISD hendooven PHITD hevlooEgsier PHITD unudsen PHITF pong et al. pong PHIH studE ied the initil growth stges of ny evh on i@HHIA y performing synhrotron Ery stteringD re)etivity nd )uoresene mesurements during the growthF e high energy Ery ws used @PR keA so tht the retor hmer hs thik qurtz wllF hendooven et al. hendooven PHIT demonstrted moile evh reE tor designed to filitte in situ qseD pD nd Ery sorption spetrosopy mesurements t synhrotron filitiesF e remote rdio frequeny plsm soure enles in situ experiments during oth therml nd plsmEenhned evhF ulug et al. ulug PHIS reported on modulr evh retorD whih llows swithing etween di'erent hrteriztion tehniquesF ttering retor modE ule is equipped with grphite dome for pD surfe sttering nd reiprol spe mpping mesurements to mximize solid ngle oveF he qse retor module is for evh proess on plnr sustrtes nd hs three upton windowsF upton ws used in smllEngle sttering experimentsD sine it hs high Ery trnspreny nd lk of sorptive impuritiesD nd it provides the neessry mehnil nd therml stilities to mintin evh system vuum t tempertures su0ient to prevent preursor ondenstionF es n exmpleD Ery surfe sttering nd re)etivity mesurements of textured ny evh on spphire were demonstrtedF qeyer et al. qeyer PHIR demonstrted smll 6cm × 6cm × 8.4cm retor hmerD whih llows performing high resolution nd grzing inidene h nd qse experiments during evhF ome groups lso demonstrted in situ h exE periment during wygh proess pong PHHTD tephenson IWWWF ythers used during evh proess unudsen PHITD uolnek PHIID llrid PHIPD llrid PHHVD qeyer PHIPF sn this seD the smple hs to e moved from the evh hmer to speilly frited ultrEhigh vuum hmer to perform in vacuo experiE mentF Chapter 2. MOON: An ALD/CVD reactor for in situ studies sn this hpterD we present new evh retor designed for performing in situ hrteriztion in the ourse of growth with speil emphsis on synhrotron rdition experimentsF pinnil support for uilding up the retor ws impleE mented y ex projet woon @exEIIExexyEHHIRAD in ollortion with visitE ing reserher hr hFhF pong from ergonne xtionl vortoryD who ws supported y oth n wrd from the xnosienes poundtion nd the FF heprtment of inergyF he retorD herefter lled wyyx @MOghGevh growth of Oxydes NnostruturesA ws designed nd developed to e used s powerful tool for in situ hrteriztion during the initil stges of mteril growth foihot PHIT with the im of inresing the omprehension nd ontrol of the growth mehE nisms governing the evh nd wygh deposition proessesF 2.2 Available in situ characterization techniques he proess tht hs een under development in the pst few yers using the wyyx retor is the growth of ny lyers nd nnostrutures y evh on vrious sustrtes @ilion oxideD pphire nd snqesAF foth evh nd wygh proesses n e performedF pigure PFI shows shemti representtion of the wyyx retor whih hs een designed to implement severl in situ hrteriztion tehniquesF he imge of the rossEsetion of the retor is shown in the eppendix f @pigF fFIAF fsillyD with the use of synhrotron rditionD this retor llows to meE sure the mount of tomi speies deposited on the sustrte y Ery )uoresene @pAD to hrterize the struturl properties nd strin t the tomi sle y grzing inidene Ery di'rtion @inEplne or outEofEplne surfe di'rtionAD to mesure the (lm thikness nd roughness y Ery re)etometry @AD to deterE mine the short rnge hemil environment nd oxidtion degree y Ery sorpE tion (ne struture @epAD to hrterize the lyer morphology y qse @we should note tht the present version of the retor is not yet optimized for qseAF elsoD t home lortory or synhrotron rdition enterD it is possile to mesure the stress generted in the sustrte y the growing (lm with optil method @suE strte urvture mesurementsAD photolumineseneD nd the optil properties y ellipsometryF illipsometry vngereis PHHW is often employed for monitoring (lm thikness nd optil mteril oe0ients during in situ synhrotron evh experiE mentsF por in situ evh experiment t the synhrotron emlineD the wyyx reE tor is pled on the hevyEduty orientle stge of the di'rtometer @lso lled di'rtometer tle @PHA in pigF PFIAD whih llows to orient the smple surfe nd djust the lterl nd vertil positions of the smpleF ottion of the sustrte round n xis perpendiulr to the smple surfe is rried out y rotting the di'rtometer tle @PHAF huring the evh experimentD while rotting the smpleD ounterErotting )nge @ISA llows the ounter rottion of the retor ody nd ll externl equipment onneted to itD thnks to slveEmster onnetion etween the ounter rottion motor @IVA nd di'rtometer motorF pigure PFIX hemti representtion of the evh retor uilt for in situ synhrotron Ery studiesX I E )uoresene detetorY P E ir pdY Q Elod lokY R E inspetion portY S E qurtz windowY TD U E preursor injetion portsY V E shower hedY WD IH E inspetion portsY II E )uoresene detetor noseY IP E movle iiu nd fe windowsY IQ E sustrte holderY IR E Ery entrne windowsY IS E ounterErotting )ngeY ITD IW E gugesY IU E gs exhustY IV E ounterErotting )nge motorY PH E di'rtometer tleF he Ery em enters into the retor hmer through IHH µm thik upton @or PHH µm thik feA window @IRA @pigF PFIAF st impinges on the smple surfe with n inidene ngle t most equl to IR • F henD the re)etedD di'rted nd sttered Ery em pss through Imm thik iiu @or RHH µm feA window @IPAD whih is IHH mm high nd hs n horizontl opening ngle equl to ITP • F he outE oming rdition is deteted with Ph pixel detetorsF Ery )uoresene yield is of fundmentl interest for studying the erly stge of growthD then we hve pid muh ttention to optimize the )uoresene detetion with stteEofEtheErt nd sensitive detetorF pigF PFI shows the implementtion of the Ey )uoresene detetor @IAF et emline ss @yvisvAD fourEelement hh )uoresene detetor with IPS e resolution @fruker plsh detetor eh SHRHA is used gitto PHITF sn order to minimize the elsti stteringD the detetor @IA is pled t WH • with respet to the inoming em diretionF elsoD to mximize the solid ngleD the detetor is mounted on trnsltion stgeY the detetor nose n pproh the smple downF Chapter 2. MOON: An ALD/CVD reactor for in situ studies he rdition is olleted through iiu window with dimeter opening equl to IQ mmD pled t distne of TV mm from the smple positionD nd removle ollimtor @dimeter equl to IQ mmA mde of iiu trgeting the smple positionF Ery re)etivity is performed y tilting the di'rtometer tle @PHAD tht holds the whole equipmentD therefore the tilt ngle is kept lower thn IH • F et the top of the retor hmerD two )nges @gpIHA @WD IHA re equipped with qurtz windowsF hey re tilted y n ngle of QS • with respet to the xis of revolution of the retion hmerF hey n e onneted to lser light soure nd to detetor for spetrosopi ellipsometry mesurementsF he top of the retor is equipped with qurtz window @gpTQA inspetion port @RAD whih is inlined y U • with respet to the retor revolution xisF yn top of this window @SAD wultiE em yptil tress ensor @wyA n e (xed for rrying out sustrte urvture mesurements nd stress nlysis in the ourse of growth ghson PHITD ploro IWWUF es exmplesD pigure PFP shows the retor implemented t the ss emline of yvisv synhrotron @prneA nd shQ emline t ipF pigure PFPX wyyx retor instlltion on ss @A nd shQ @A emlines in yvisv @intEeuinD prneA nd ip @qrenoleD prneA synhrotron entresF 2.3. ALD implementation with the MOON reactor 29 2.3 ALD implementation with the MOON reactor pigure PFQ shows synopsis of the wyyx retor nd gs lines onneted to the retorF pigure PFQX he top of the retor9s hmer is onneted to two gs linesF yne for injeting metl preursor @left gs lineAD one for injeting theoxidnt @x 2 y or r 2 y for ny evhA or purge gs @x 2 A @right gs lineAF he gs lines re onneted to shower hed whih is used for otining n uniform distriution of retnts in the retor hmer ove the sustrteF he sustrte holder is pled on top of the heting stgeD whih is onneted to the di'rtometer tleF fypss lines for hinD x 2 yD nd x 2 gses re onneted to the exhust pump through furne heted to temperture ove the metl preursor deomposition @SHH • gAF he top of the retor9s hmer is onneted to two gs linesF yne for injeting metl preursor @left gs line in pigF PFQAD one for injeting the oxidnt @x 2 y or r 2 y for ny evhA or purge gs @x 2 A @right gs lineAF he gs lines re onneted to shower hedD whih is used for otining uniform distriution of retnts in the retor hmer ove the sustrteF hen the gses enter the retor hmerD they reh the sustrte surfe heted up to the evh proess tempertureF he sustrte nd sustrteEholder re pled on top of the heting stgeD whih is onneted to the di'rtometer tleF e lso use ypss gs lines for hinD x 2 yD nd x 2 gsesF he lines re onneted to the pump via furne @sruerA heted up to the temperture of the metl preursor deomposition @SHH • gAF nreted gses nd retion produts from the retor hmer re lso pumped down through the sruerF e detiled synopsis of the gs lines onneted to the retor hmerD s well Chapter 2. MOON: An ALD/CVD reactor for in situ studies s ypss gs linesD is shown in the (gure PFRF he gs )ow through the lines is pigure PFRX qs lines onneted to the retor hmer nd ypss gs linesF he si elements of the sheme re indited in the (gureF ell gs )ows re ontrolled y the mss )ow ontrollersF ypening nd losing of pneumti vlves re rried out on the ontrol pnelF ontrolled y pneumti vlves nd y mssE)ow ontrollers @wpgsAD the pressure inside the gs lines nd the retor hmer is ontrolled y pressure gugesF ome prts of the retor re heted up nd mintined t onstnt temperture level round UH • g @for instneD ll hin line re heted up to void hin ondenstionAF fypss lines re needed for gs pressure nd )ow stiliztion efore its injetion into the retor hmerF e pipeD whih goes from the retor hmerD nd ll ypss gs lines re onneted to the heted prt of the pipe @for in)mmle preursor deompositionA nd then to the pumpF gontrol of the elements shown in the digrmD s well s ontrol of the temE pertureD gs )owD nd pressure is rried out using dedited softwre essile vi ontrol pnel on the omputer @see pigsF fFQ nd fFR in ppendix fAF he entire proess is utomted nd llows to perform onseutive evh experiment ontinuously yle fter yleD nd lso stop evh proess t ny yle numer or t ny step during the evh yleF rerefterD we fous on the di'erent omponents of the retor shown in the following setions of the hpterF 2.3.1 Water evaporator he injetion of wter vpor into retor hmer is rried out using wter evportorF he sheme of wter evportor nd retor hmer onnetion is shown in (gure PFS @the di'erent omponents re lelled with numersAF he pigure PFSX hemti representtion of wter evportor whih is tthed to the retor hmerF he wter evportor onsists of twisting ylindril prt @IA with distilled wter insideD (xed ylindril frmework @PAD nd pressure guge on top @QAF he wter vpor )ow is ontrolled y mnul needle vlve @RA nd pneumti vlve @SAF he nitrogen )ow is ontrolled y pneumti vlve @TAF foth gs lines re onneted to the retor hmer @UAF evportor itself onsists of srewEin ylindril ontiner @IA with the deionized wterD (xed ylindril frmework @PAD nd pressure guge @QA on top @pigF PFSAF yperting rnge of the mesured pressure for the pressure guge is from H to PSH mrF he dependene of the wter vpor prtil pressure on the wter temperture is desried y the entoine eqution peight PHHSX p[mbar] = 1.33 * 10 A-B/(C+T ) , @PFIA where the temperture is in degrees gelsius Chapter 2. MOON: An ALD/CVD reactor for in situ studies e losed when wter vpor )ow is injeted into retor hmer @r 2 y pneumti vlve @SA is openAD nd vice versaD if only nitrogen is injetedF he wter vpor )ow is ontrolled y the mnul needle vlve @RA @pigF PFSAF fy inresing the numer of turns of vlve @RAD the size of the perture inside this vlve inresesD nd therefore the wter vpor )ow through this hole inresesF sf the x 2 pneumti vlve @TA is losed @the retor hmer @UA is isolted from )owing er or hin gsesAD nd if r 2 y pneumti vlve @SA nd r 2 y mnul vlve @RA re openD the retor hmerD whih hs volume reactor D is onneted with the wter evportor volume @to prevent pumping from the retor hmerD the pneumti vlve etween retor hmer nd the pump shown in (gF PFR is losedAF he retor hmer pressure p reactor is ontrolled y pressure gugeF nder the ondition tht the pressure inside retor hmer p reactor is lower thn the wter vpor pressure inside the evportor @p water evaporator AD wter vpor strts )owing into the isolted retor hmerF sf the se pressure of the retor hmer @see the inset of (gF PFT@A for H sA is set round HFS mr @p reactor < p water evaporator A nd the injetion of wter vpor into the retor hmer is strtedD the retor hmer pressure p reactor will inreseF he inset of (gure PFT@A shows the rte of inrese of the retor hmer pressure for di'erent mnul vlve @RA opening positions nd wter pressure equl to QQFH mr t room temperture @PSFV • gAF pigure PFTX @A etor9s hmer pressure rte of inrese s funtion of the numer of turns of the mnul needle vlveF snsetX etor9s hmer pressure s funtion of time for di'erent numer of turns @openingA of the mnul needle vlveF he slopes of the liner urves give the retor hmer pressure rte inrese y time unitF @A ghnge of r 2 y evportor pressure versus injetion time for di'erent numers of needle vlve turnsF sn the inset of pigF PFTD we oserve tht y injeting wter vpor into the retor hmer @UAD the pressure inside inreses linerly s funtion of time in the rnge of few hundred of seondsF he slopes of the liner urves re the time derivtive of pressureD it gives the rte of inrese @mrGminA of the retor hmer pressureF he pressure rte hnges y hnging the opening @numer of turnsA of the mnul vlve @RAF he (gure PFT@A shows the inrese of retor9s hmer pressure rte s funtion of the numer of turns of the mnul vlveF he vlue of eh point on the urve orresponds to the slope of the liner funtions p reactor @timeAF he pressure rte inrese vs the numer of turns of the mnul needle vlve @pigF PFTD experimentl pointsA n e pproximted y qudrti funtion @(tAD sine the dimeter of the vlve irulr perture inreses in proportion to the squre funtion of numer of vlve turnsF gonsequentlyD the pressure inside the wter evportor dereses when wter vpor injetion strts into the retor hmerF he equilirium pressure inside wter evportor is lne etween the inE rese nd derese of pressure for two resonsF pirstD the pressure inside the wter evportor dereses due to the injetion of wter vpor from the evportor into the retor hmer @if p reactor < p water evaporator AF eondD the wter evportor pressure inreses due to the evportion of new moleules from the liquid wter phse inside the wter evportorF xote tht n inrese of the wter vpor pressure inside the wter evportor n our up to the vlue determined y the eqution PFIF pigure PFT@A shows notiele derese of evportor pressure versus injetion time for lrge numer of vlve turns @VEIH turnsAF snstedD the evportor pressure drop is lower for the lower numer of vlve @RA turns @QEU turnsA nd the evportor pressure rehes plteu due to the evportion of wter moleulesF pinllyD when the vlve is slightly open @IEP turnsAD the evportor pressure lmost does not hngeD euse the pressure lne is kept y evportion rte of new wter moleules in the evportorF epprentlyD the evportor pressure for smll numer of vlve turns nnot e n indition of the ft tht wter vpor is injeted into the retor hmer or notF ine there is no wter evportor pressure drop for the se of I nd P vlve turns @(gF PFT @AAD t the sme timeD the wter )ow n e injeted into the retor hmer @(gF PFT @AAF xeverthelessD for lrger numer of mnul vlve turns @more thn PA nd for su0ient time @less thn HFS minuteAD the evportor pressure deresesD this ft indites the injetion of wter vpor into the retor hmerF 2.3.2 DEZn injection sn the present studyD the nEpreursor is diethylzin n@g 2 r 5 A 2 @hinAF hin is highly pyrophori orgnozin ompound onsisting of zin enter ound to two ethyl groupsF et room tempertureD hin is liquid nd it ignites spontneously in irF pigure PFU shows piture of the ulerGevportor ox eing omposed of hin ontinerD gs linesD pressure gugesD nd vlvesF he numers in oth (gures PFU nd PFV indite the di'erent omponents of the hin ontiner oxF por sfety resonD only smll mount of hin @PH mvD ≈ 24gA ws kept inside the preursor ontiner @SA @pigF PFUAF he re(ll of the ontiner is performed inside Chapter 2. MOON: An ALD/CVD reactor for in situ studies

x 2 glove ox with syringeF hin preursor ontiner n e used s uler pigure PFUX e piture of the ulerGevportor oxF he ox omprises pneumti vlves @ID PD RD UD WAY mnul vlves @QD VAY ulerGevportor pressure guge @TAY mnul needle vlve @p vFA to ontrol the pressure inside the ulerF or evportor @pigF PFVAF hen the preursor ontiner is used s uler @pigF PFV@AAD n inert er gs is injeted into the ontinerD mixes with hinD nd rries the hin moleules out of the ontinerF hen the preursor ontiner is used s n evportor @pigF PFV@AAD hin moleules re evported y heting the ontinerF hin uler @SA @pigsF PFU nd PFVA is onneted with two gs linesF neumti vlves @IAD @PAD @RAD @UAD nd @WA ontrol er nd hin gs )owsF hese pneumti vlves work in two modesX 4the vlve is open4 @green olored vlves in (gure PFVA or 4the vlve is losed4 @gry olored vlves in (gure PFVAF pigure PFV@A nd PFV@A show mnul shutEo' vlves @QA nd @VA ner the entrnes to hin ontinerF sf the retor is not usedD vlves @QA nd @VA lwys must e losedD for sfety reson nd efore dismounting the hin ontinerF e prtil pressure of the er nd hin mixture inside the uler or hin inside the evportor is mesured y pressure guge @TAF he ulerGevportor pressure vlues n e monitored y ontrol pnel on the omputer sreenF 2.3.2.1 DEZn container as a bubbler sn seD when hin ontiner is used s ulerD n inert gs @erA is )owing through uler ontining liquid hin to trnsport it inside the retion hmE erF pigure @shemtiA PFV@A shows the working priniple of the ulerF neuE mti vlves @IAD @PAD @UAD nd @WA nd mnul shutEo' vlves @QA nd @VA must e opened during hin injetionD when er rrier is injeted inside hin ontiner @SA pigure PFVX hemti representtion of two ses of using diethylzin @hinA onE tinerX @A s ulerD inert er gs is injeted into hin ontinerD mixes with hin nd rries the hin moleules @A s n evportorD hin moleules re evported y heting the ontinerF fulerGevportor ox onsists of pneumti vlves @ID PD RD UD nd WAY E mnul vlves @QD VAY E ulerGevportor pressure guge @TAY mnul needle pressure vlve @p vFAY gs line outlet @IHAF @pigsF PFU nd PFV@AAF er )ows in gs lines through pneumti vlves @IA nd @PAD nd mnul shutEo' vlve @QAD nd enters inside the hin ontiner @SAF he left gs tue inside hin ontiner @SA is immersed in liquid hinF er is eing mixed with hin nd rries hin moleules through the right short hin ontiner tueF henD mixture of er nd hin )ows in gs line through the perture of mnul shutEo' vlve @VA nd through the pertures of pneumti vlves @UA nd @WAF he pressure vlues of er nd hin mixture re mesured y pressure guge @TAF he vlues of the pressure inside the uler n e hnged y rotting mnul pressure vlve @p vFAF huring er gs injetion inside hin ontinerD pneumti vlve @RA is losedF sf this vlve is losedD er gs )ows only into the ulerF sf vlve @RA is openD er gs is split into two )owsX one )ow goes through pneumti vlve @PAD nother )ow goes through pneumti vlve @RAF lve @RA is used to purge the er C hin gs line fter eh depositionF hen using hin ontiner s ulerD we ontrol the )ow nd pressure of er nd hin mixtureD ut not pure hinD then it is di0ultD if not impossileD to know the ext mount of hin @or prtil hin prtil pressureAF elsoD when the ontiner emptiesD the mount of hin trnsported with er is hnging @deresingA s the level of liquid hin is deresingF hese re the min disdvntges of using hin ontiner s ulerF he hrdwre on(gurtion for the present study is di'erentD pure hin is loded inside ontiner nd is diretly trnsported through heted gs line to the retion hmer without using erF sn this seD hin ontiner is used s n evportorF 2.3.2.2 DEZn container in evaporator mode hen hin ontiner is used s hin evportorD er gs is not injeted into the hin ontinerD there is no rrier gsF snstedD ll the mount of hin ontiner nd supplied gs linesD pled inside the evportor ox @desried hereE fterAD re heted up to the temperture ev. F sn our experimentsD the evportor ox temperture ev. ws UH • gD howeverD this temperture is di'erent from the rel hin temperture DEZn D sine some of the het is lost due to poor het trnsE fer etween the heter nd hin evportorF sn the rtile y qersimhuk et al. qersimhuk PHIRD one (nds the experimentl dt nd simultion of hin sturted vpor pressureF pigure PFWX turted vpor pressure of diethylzin or hin @red dshed lineA nd wter @lue ontinuous lineA s funtion of tempertureF he lue irle nd red tringle show the typil pressure vlues tht we use during the evhF pigure PFW shows tht sturted vpor pressure of hin inreses s funtion of tempertureF por given tempertureD the sturted vpor pressure of wter nd etone is higher thn the sturted vpor pressure of hin @pigF PFWAF por instneD to hieve sturted hin vpor pressure ove SH mrD the temperture of liquid hin should e higher thn RH • gF pigure PFV @A shows the working priniple of the evportorF huring pure hin gs injetion from hin ontiner @SAD pneumti vlves @UA nd @WAY nd mnul shutEo' vlve @VA must e openedF ine er is not usedD pneumti vlves @IAD @PAD nd @RAY nd mnul shutEo' vlve @QA re losedF ure hin )ows in gs line through the perture of mnul shutEo' vlve @VAD nd through the pertures of pneumti vlves @UA nd @WAF he pressure vlues of pure hin gs re mesured y pressure guge @TAF he hin ontinerD gs linesD vlvesD nd pressure guge re inside the therE mlly insulted ox @green retngle in the pigsF PFV@A nd PFV@AAF he therE pigure PFIHX fulerGevportor oxF he thermlly insulted ox onsists of two prtsX (xed se @A nd lid for losing the oxF hen ll the preprtions with mnul vlves re (nishedD the ulerGevportor ox is overed y temperture insulted lid @AF ell ulerGevportor ox is heted up to ev F mlly insulted ox onsists of two prtsX (xed se @pigF PFIH@AA nd lid to lose the oxF hen ll the opertions with mnul vlves re (nishedD the ulerGevportor ox is losed @pigF PFIH@AAF hen hin gs )ows out the ulerGevportor oxD it enters into hin mss )ow ontroller through outlet gs line prtF he evportorGuler ox is heted up to the temperture ev @UH • gA using heter nd fn @for otining n even tempertureA inside the oxF he temperture of liquid hin DEZn @RS • gA inside evportor @SA @pigF PFUA is lower thn ev @UH • gA due to therml lossesF he tul hin temperture DEZn is lulted using the experimentl vlue of hin pressure @p ev AF por the hin temperture DEZn = 45 • gD hin sturted vpor pressure inside evportor t the equilirium is lose to p ev = 70 mrF Chapter 2. MOON: An ALD/CVD reactor for in situ studies 2.3.2.3 DEZn injection into the reactor chamber in the evaporator mode iture PFII nd shemti PFIP show the gs lines system whih onnets hin evportorGuler oxD retor hmerD nd ypss lineF hin is trnsported to the retion hmer through 6 mm dimeter gs lines @IHAD nd @IQA @pigsF PFII nd PFIPA nd selfEheted )exile hose IP from Winkler GmbHD oth in 316L stinless steelF pigure PFIIX iture of hin evportor oxD ypss gs line nd retor hmerX IH E outlet gs lineY II E diethylzin mss )ow ontroller @hin wpgAY IP E hosesY IQ E multivlve gs lineY IRD IT E QEports highEspeed pneumti multivlveY IS E retor hmerY IU E ypss line pressure gugeY IV E mnul ypss pressure needle vlveF he prt of hin wpg onneted with gs line is heted y )t resistive heter 4wpg heter4F yutlet gs line prt goes out from hin evportor ox nd enters into hin wpgF e highEtemperture hin mss )ow ontroller @hin wpgA is lolized eE tween the gs line nd the hose @hin wpg eer pgEeUVHgr from rithi wetlsD vtdF IIAF hin wpg @IIA regultes the hin vpor )ow rteF he vlues of hin )ow ontrolled y hin wpg n e hosen etween H nd QH smF he )ow vlue is given in perentsD IHH% orresponds to QH smD other vlues of the )ow re onneted with the )ow expressed in sm y eqution PFPX

f DEZn M F C [%] = (f DEZn M F C [sccm]/30sccm) * 100%, @PFPA
fetween the )exile hose @IPA @pigsF PFII nd PFIPA nd the retor hmer @ISAD QEports highEspeed pneumti multivlve mnifolds @IRA nd @ITA re pledF hey regulte the )ow inside the retion hmer @ISA or inside the hin yEpss gs line when hin does not )ow through the retorF he QEports highEspeed pigure PFIPX hemti representtion of hin evportor oxD ypss gs line nd retor hmerX ID PD RD UD W E pneumti vlvesY QD V E mnul shutEo' vlvesY S E diethylzin @hinA evportorY T E evportor pressure gugeY IH E outlet gs lineY II E diethylzin mss )ow ontroller @hin wpgAY IP E hosesY IQ E multivlve gs lineY IRD IT E QEports highEspeed pneumti multivlveY ISEretor hmerY IU E ypss line pressure gugeY IV E mnul ypss pressure needle vlveF pneumti multivlve is omintion of two highEspeed vlves @IRA nd @ITA whih ontrol the durtion of hin injetion inside the retor hmer @ISAF he gs line etween ulerGevportor ox @pigsF PFII nd PFIPA nd retor hmer @ISA re heted to void hin vpor ondenstion into liquid hin @pigF PFWAF yutlet gs line @IHA onnets hin ulerGevportor ox nd hin wpgD it is heted up to the temperture out F hin wpg @IIA is heted up to the temE perture DEZn M F C F he selfEheted )exile hose @IPA onnets hin wpg nd highEspeed pneumti multivlve gs lineD the hoses re heted up to the temperE ture pipes F he highEspeed pneumti vlves @IRA nd @ITA @pigsF PFII nd PFIPA re heted up to the temperture ALD v. F he temperture of hin gs line prts @ out D DEZn M F C D pipes D nd ALD v. A re higher thn the temperture of vpor hin DEZn to void hin ondenstionF le PFP shows typil temperturesD whih we use during ny evhF le PFPX ypil tempertures for hin preursor gs genertion nd trnsport during ny evhF ev. @ • gA out. @ • gA DEZn M F C @ • gA pipes @ • gA ALD v. @ • gA UH UH US UU SH huring hin injetion into the retor hmerD hin vpor )ows through gs line outlet @IHA @pigsF PFII nd PFIPAD hin wpg @IIAD hose @IPAD the perture of opened pneumti vlve @IRAD nd enters into the retor hmer @ISAF fefore hin injetion during evh proessD the vlue of hin )ow should e onstnt nd the pressure of hin in gs line efore the retor hmer hs to e higher thn retor hmer pressureF elsoD it tkes time for the hin wpg to reh the set point vlue of )ow fter its openingF endD if the pressure inside hin gs line is lower thn inside retor hmerD there is time dely efore the pressure inresesF o hieve reproduile nd stle proess of hin injetion inside retor hmerD we use ypss gs lineF 2.3.2.4 DEZn bypass line and injection inside reactor chamber fypss gs line @pigF PFIPA is used for two resonsF he min reson is to reh onstnt vlue of hin )ow efore hin injetion inside the retor hmerF he seond reson is to set hin pressure inside ypss gs line efore retor hmE er p bypass in order to otin pressure higher thn the retor hmer pressure p reactor F por setting the ypss pressure @p bypass A needle vlve @IVA is usedF es shown in susetion PFRFP @pigF PFPHAD the vlues of hin )ow inrese s funtion of time fter hin injetionD when wpg @IIA @pigF PFIPA hs een openedF yne n notie jump of )ow vlues when hin wpg is openedD then these vlues go to set point vlue @see f DEZn urve @irled in red ovlA in (gF PFPH in susetion PFRFPAF por etter hin )ow ontrolD nd therefore ontrol of hin quntity injeted into the retor hmer @ISA during evhD hin )ows into the pump through ypss line nd then is injeted into the retor hmer @ISAF sf the hin )ow is lowD it tkes some time to ful(ll gs line with hin nd inrese the pressureF huring )owing hin through the ypss lineD pneumti vlve @WA nd @ITA re opened @pigF PFIPAF wnul vlve @IVA keeps the vlues of pressure inside gs line prt in etween hin wpg @IIA nd mnul vlve @IVAF fypss pressure guge @IUA monitors the pressure inside this volumeF sf mnul vlve @IVA is openedD nd the position of the vlve is hosenD the pressure inside gs line fter hin wpg @IIA nd efore vlve @IVA strts to inreseD when hin wpg hs een openedF his pressure inrese for di'erent positions of mnul needle vlve @IVA is shown in (gure PFIQD the hin wpg @IIA set vlues were identil @hin )ow f DEZn ws SFI smA F yne n see tht this pressure inreses nd rehes onstnt vlueD whih is determined y the opening of the mnul needle vlve nd the hin wpg set point vlueF he position of mnul vlve @IVA @pigF PFIPA must e hosen efore tomi lyer deposition proessF por instneD if the onstnt nd stilized vlue of the ypss pressure is IP mr @for given opening of the needle vlve @IVA nd hin wgp @IIA vlue equl to SFI smA then the vlue of the ypss pressure for QH seonds hin injetion is IIFQ mrF efter hin hs )owed into the ypss gs line during the time t DEZn stabilization D the vlue of hin )ow ontrolled y hin wpg @IIA is stilized nd the ypss pressure is higher thn retor hmer pressureF hen time t DEZn stabilization is overD pneumti vlve @IRA is utomtilly opened nd pigure PFIQX hin pressure inrese inside the ypss gs line s funtion of time @hin wpg II set vlue equl SFI smAF he H s point orresponds to the moment when hin wpg ws openedF ih urve orresponds to di'erent needle vlve IV openingD whih ontrols the ypss line pressureF @ITA is losedD nd hin is injeted into the retor hmerF 2.3.3 Ar, N 2 , and N 2 O gas injection, pumping xitrogen @x 2 A ndGor rgon @erA re used s rrier ndGor purging gses deE pending on the proess nd oth re supplied to the retion hmer through the nEpreursor or yEpreursors linesF x 2 yD x 2 D nd er were supplied inside the reE tor hmer y gs distriution pnel designed y hF he frros nd frited y ymiron tehnologiesF he gs pnel is minly mde with T mm dimeter stinless steel piping nd metl gsket fe sel (ttings to ensure the tightnessF pigure PFIR shows the gs pnelF prom the gs ylinder @inputA to the retion hmer @outputAD eh gs line from the gs pnel onsists ofX I E mnometer inditing the gs ylinder pressureY P E gs pressure regultor to redue the input pressure to the desired vlue t the outputY Q E yEpss mnul diphrgm vlve to purge eh gs line with x 2 Y R E mnometer inditing the gs line pressureY S E pneumti diphrgm vlve to shut o' the gs line from the inputY T E sfety vlve to relese unexpeted high pressure inside the gs lineY U E yEpss mnul diphrgm vlve to hek nd lirte the wss plow gontroller @wpgA for eh pigure PFIRX qs pnelX @IA mnometer inditing the gs ylinder pressureD @PA gs pressure regultor to redue the input pressure to the desired vlue t the outputD @QA yEpss mnul diphrgm vlve to purge eh gs line with x 2 D @RA mnometer inditing the gs line pressureD @SA pneumti diphrgm vlve to shut o' the gs line from the inputD @TA sfety vlve to relese unexpeted high pressure inside the gs lineD @UA yEpss mnul diphrgm vlve to hek nd lirte the wss plow gontroller @wpgA for eh line using x 2 D @VA wss plow gontroller @wpgA to mnge the )ow rte of the gs t the outputD @WA pneumti vlve to shut o' the gs line from the outputF line using x 2 Y V E wss plow gontroller @wpgA to mnge the )ow rte of the gs t the outputY W E pneumti diphrgm vlve to shut o' the gs line from the outputF he (rst line @x 2 lineA is dedited to x 2 gsD it is divided into Q lines used for injeting rrier gs nd purge gs inside the retion hmerF x 2 line lso hs yEpss line with wss plow weter @wpwA employed for the mss )ow ontroller @wpgA lirtionF he seond line @er lineA nd third line @x 2 y lineA re dedited to er nd x 2 yD respetivelyF he fourthD (fth nd sixth lines re spre lines used to supply other gses for other growth proesses to grow di'erent mterilsF pigure PFIS shows gs linesD wter pipesD nd x 2 y gs ylinderD used for evh proessF er nd x 2 gs lines @pigF PFIS@AA nd x 2 y gs ylinder @pigF PFIS@AA re onneted to gs pnel @pigF PFIRAF he ompressed ir line @pigF PFIS@AA is onE neted to the pneumti vlve distriution pnel y plsti hosesF neumti vlve distriution pnel is remote ontrol pnel used for openingGlosing the pneumti vlvesF wo wter pipes @pigF PFIS@AA re onneted to the pump for ooling it pigure PFISX qs linesD wter pipesD nd x 2 y gs ylinderD used for tomi lyer deposition @evhA proessF he ompressed ir line @A is onneted with pneumti vlve pnel y plsti hosesF er nd x 2 gs lines @A nd x 2 y gs ylinder @A re onneted to the gs pnel @pigF PFIRAF while funtioningF elsoD the pump is onneted to the uilding exhust gs lineF e dry multiEstge roots pump evgeiv eh IPPv is used to reh su0E ient se pressure nd exhusts ll the proess rrier gs nd yEprodutsF en tement system is used downstrem of the pump to deompose residul hin yEprodutsF his tement system onsists of QITv stinless steel tuulr furE ne resistively heted t SSH • g i.e. ove the hin yEproduts deomposition temperture round 500 • g tnuki PHHWF 2.3.4 Substrate heating system herml tomi lyer deposition @evhA proess is rried out t given sustrte temperture substrate tht is most often ove room temperture @AF husD sustrte is loded inside the retor hmer nd heted up to the temperture substrate with heting suseptorF e shemti representtion of sustrte heting system is shown in the (gure PFITF e sustrte @QA is pled on sustrte holder @PA outside of the retor hmerF henD the sustrte holder nd sustrte re loded into the retor hmer nd pled on the sustrte heter @IAF he eletril urrent )owing into the resistive wire inside the heter stge @IA hets up the sustrte holderF he power vlue or more preisely the urrent nd voltge vlues re ontrolled y the heter power eletroni pnelF pigure PFITX hemti representtion of sustrte heting setup during @A evh proess nd @A sustrte surfe temperture mesurementsX @IA heterD @PA suE strte holderD @QA sustrteD @RA uEtype thermooupleD @SA retor )ngeD @TA mulE timeterF @A e silion sustrte @QA is glued to the sustrte holder @PA with silver psteD uEtype thermoouple @RA is onneted with multimeter @TA for sustrte temperture mesurementsF he thermoouple @RA is glued to the enter of silion sustrte @QA using silver psteF he other side of the thermoouple is onneted with retor )nge @SAD nd then to the multimeter @TAF he vlues of heter temperture heater re mesured y thermooupleD pled inside the heter nd onneted to the heter upper surfeF he vlues of the urE rent nd voltge pplied to the heter wire re shown on heter power eletroni pnelF he setpoint heter temperture setpoint heater is de(ned on the ontrol pnel sreenF he experimentl vlue of the heter temperture @ heater A is lwys omE pred with the setpoint heter temperture @ setpoint heater A nd heater is hnged y feedk ontrolF hue to the temperture grdientD the temperture of the sustrte is di'erent from the temperture of the heterD depending on the mteril nd thikness of sustrteF o study this e'etD experimentl vlues of sustrte temperture s funtion of the setpoint heter temperture ws mesuredF he x 2 )ow nd reE tor hmer pressure were lso vriedF sn this experimentD silion sustrte @QA @pigF PFIT@AA ws glued to the sustrte holder @PA with silver psteF e used uE type thermoouple @RA onneted with multimeter @TA for sustrte temperture mesurementsF he thermoouple @RA ws glued to the enter of the silion suE strte @QA with silver psteF he other side of the thermoouple ws onneted with retor )nge @SAD nd from there to the multimeter @TAF fefore the sustrte temE perture mesurementsD vuum nd then evh experimentl onditions @pressureD tempertureD nd x 2 )owA were hievedF he x 2 )ow ws set to vlue equl to IHH smD the retor hmer pressure ws either equl to T mr or PH mrF pigure PFIU@AA shows the experimenE tl heter tempertureD sustrte temperture @for retor pressure p reactor chamber equl to T mr or PH mrA s funtion of the setpoint heter tempertureF pigure PFIUX hependene of the sustrte nd heter @lk squresA temperturesD the di'erene in sustrte nd heter temperturesD nd the pplied power to the heter from set point heter temperture @AD retor pressure @AD nd nitrogen )ow through retor hmer @AF hen setpoint heter temperture ws vried @AD the retor pressure ws set to T mr @red tringles onneted y lineA nd PH mr @lue irles onneted y lineAD nitrogen )ow ws set to IHH smF hen retor pressure ws vried @AD the setpoint heter temperture ws set to PSH • gD nitrogen )ow ws set to IHHH smF hen nitrogen )ow through retor hmer ws vried @AD the setpoint heter temperture ws set to PSH • gD retor pressure ws set to T mrF st should e noted tht time is needed for the stiliztion of the temperture of oth sustrte heter nd sustrte for given experimentl onditionsF hen the heter temperture setpoint vlue setpoint heater is hosenD (rstD the heter temE perture heater rehes the onstnt vlue nd does not hngeD then sustrte temperture substrate rehes onstnt vlue nd does not hnge with timeF ell experimentl vluesD shown in the (gure PFIU were mesured when the heter temE perture nd sustrte temperture were stilized @i.e. they rehed onstnt vlue tht does not hnge with timeAF he (gure PFIU@A shows tht the heter tempertureD s mesured y the therE moouple inside the heterD is liner funtion of the setpoint heter tempertureF woreoverD the slope of this liner funtion is ID this mens tht the experimentl vlues of the heter temperture re equl to its setpoint vlues when the temE perture is stilizedF fesidesD the sustrte temperture is lower thn the heter temperture ndD for the retor pressure p reactor = 20 mrD the di'erene etween the heter temperture nd sustrte temperture is lower thn for p reactor = 6 mrF he di'erene etween the heter temperture heater nd the sustrte temperture substrate inreses s funtion of the setpoint heter temperture setpoint heater F e sustrte older thn the heter is likely due the ooling of the sustrte surfe y x 2 gs )owF por higher retor pressure @PH mrAD higher heting power is to e pplied to reh the sme heter tempertureF e investigted the in)uene of retor pressure on the sustrte temperture when x 2 )ow through retor hmer is onstnt @f N 2 aIHHHsmA nd the heter setpoint temperture is onstnt @ setpoint heater aPSH • gAF sn our evh experimentD )owing x 2 during purging stepD in etween preursors injetionD tkes time @usully RS sAY IHHH sm nitrogen )ow vlue ws hosen euse it is the most ommonly used x 2 )ow vlue during our evh proessF pigure PFIU@AA shows tht the temperE ture of the heter s funtion of the retor pressure is onstnt @lose to heter setpoint tempertureAF por higher retor pressure vluesD higher power must e pE plied to the heterD to reh the setpoint temperture setpoint heater F he sustrte temperture is lower thn the heter tempertureD ut inresing retor hmer pressureD the di'erene etween these two tempertures deresesF e lso investigted the in)uene of the vlue of x 2 )ow through retor hmE erD on the sustrte temperture when retor pressure is onstnt @p reactor aT mrA nd heter setpoint temperture is onstnt @ setpoint heater aPSH • gAF pigure PFIU@AA shows tht for di'erent nitrogen )ow vluesD the heter temperture is onE stntF por the seleted setpoint heter temperture nd retor pressure vluesD the di'erene in the temperture of the heter nd the sustrte is pproximtely onE stnt @IS • gA for di'erent x 2 )ow vluesF he heter power is lso lmost onstnt for di'erent x 2 )ow vluesF 2.4 Atomic layer deposition process feforeD during nd fter evh proessD erD hinD r 2 yD x 2 yD nd x 2 gses n e usedF he shemti onnetion of gs lines with retor hmer nd the pump is shown in the (gures PFIV nd PFIWF etement system @sruerA onsisting of tuulr furne heted t scrubber = 550 • gD is pled efore the pumpF he sruer is indited s two retngles in (gures PFIV nd PFIWF erD pure hinD mixture of er nd hinD r 2 yD x 2 yD nd x 2 n e injeted into the retor hmerF he retor exhust is onneted to the sruer nd eyond to the pumpF elsoD gs injetion n our diretly into the sruer through ypss lineF hinD x 2 yD nd x 2 ypss gs lines re onneted to the sruer nd re used eforeD during or fter the evh proessF por ny evhD we used hin s n preursorD x 2 y or wter s n oxidntD x 2 s purging gsF x 2 y is lso used s gsD injeted into the sruer through the ypss lineD to deompose hin whih did not retF hree gses @hinD x 2 yD nd x 2 A re onneted to the retor hmer y the gs linesD they re lso onneted to the sruer y the ypss gs linesD s it is shown in the (gures PFIV nd PFIWF r 2 y gs line is only onneted to the retor hmerF fypss gs lines re used for the gs )ows stiliztion efore injetion into the retor hmerF es for x 2 nd x 2 y gsesD they re onstntly injeted into the retor hmer or ypss lineF he )ows of x 2 nd x 2 y gses re regulted y mss )ow ontrollers @wpgAF o sve the preursorD the injetion of hin into the ypss line is strted some time t DEZn stabilization efore hin injetion into the retor hmerF he hin injetion into ypss gs line is needed for hin )ow stiliztion nd hin pressure inrese until the vlue p bypass @see susetion PFQFPFRAF x 2 y gs injetion into the sruer through the ypss line is lso needed for urning the hin moleules @hin rets with x 2 y inside the sruerAF yne ny evh yle inludes four steps of gses injetion into retor hmerX hin injetion @sAD hin purge y x 2 @ssAD oxidnt injetion @x 2 y or r 2 yD sssAD nd oxidnt purge y x 2 @sAF pigures PFIV nd PFIW show two series of drwingsD on the left they demonstrte the gs )ows into the retor hmerD on the right the gs )ows into the ypss linesF he upper urves re plotted s funtion of timeF ih numer on the urve @sD ssD sssD or sA orresponds to the di'erent evh yle stepsF pigures PFIV nd PFIW lso show shemti onnetion of gs lines to the retor hmer nd the pumpD nd gs )ows for eh evh yle step @sD ssD sssD or sAF he gs )ows re shown y di'erent olor tiksF 2.4.1 ZnO atomic layer deposition process when N 2 O is used as an oxidant (g. 2.18) hen x 2 y is used s n oxidntD nother two gses re used for evh proessX diethylzin @hinA s n preursorD nd x 2 s purging gsF he evh yle is divided into four steps of injetion into the retor hmerX hin injetion @step sAD hin purge y x 2 @step ssAD x 2 y injetion @step sssAD nd x 2 y purge y x 2 @step sAF huring step s of one evh yleD hin is injeted into the retor hmer @pigF PFIVD sAD it is not injeted nymore through the ypss @residul hin gses is eing pumped from ypss gs lineAF x 2 y nd x 2 re injeted through the ypss line into the sruerF huring step ssD x 2 is injeted inside the retor hmer for purging fter hin @pigF PFIVD ssAD it is not injeted into the sruer through the ypss lineF x 2 y is injeted into the sruer through the ypss lineD hin nd r 2 y re not injeted t llF huring step sssD x 2 y is injeted into retor hmer @pigF PFIVD sssAF x 2 is injeted into the sruer through the ypss lineD hin is not injeted t llF et lstD during step sD x 2 is injeted inside retor hmer for purging fter x 2 y @pigF PFIVD sAF x 2 y is injeted into the sruer through the ypss lineD the injetion of hin into ypss line is strted t time tat DEZn stabilization efore hin injetion into the retor hmer @step sAF pigure PFIVX hemti desription of the gses injetion during evh proessD when hin is used s metl preursor nd x 2 y is used s n oxidntF he three gsesD hinD x 2 yD nd x 2 D n e injeted in the retor hmeror diretly in the sruer y the ypss gs linesF r 2 y gs line is onneted to the retor hmer onlyF he evh yle is divided into four steps of injetion into retor hmerX hin injetion @step sAD hin purge y x 2 @step ssAD x 2 y injetion @step sssAD nd x 2 y purge y x 2 @step sAF golor rrows indite gs )ows @ville onlineAF 2.4.2 ZnO atomic layer deposition process when water is used as an oxidant (g. 2.19) hen r 2 y is used s n oxidntD nother two gses re used for evh proessX diethylzin @hinA the metl preursorD nd x 2 s purging gsF x 2 y gs injeted into the sruer during the ll evh proess through ypss line to ret with hin for hin deompositionF he evh yle n e divided into four steps of injetion into retor hmerX hin injetion @step sAD hin purge y x 2 @step ssAD r 2 y injetion @step sssAD nd r 2 y purge y x 2 @step sAF huring step s of one evh yleD hin is injeted into retor hmer @pigFPFIWD sAD hin is not injeted through the ypss @residul hin gses is eing pumpedAF x 2 y nd x 2 re injeted through ypss line into the sruerF r 2 y is not injeted t llF huring step ssD x 2 is injeted inside the retor hmer for purging fter hin pulse @pigFPFIWD ssAD ut it is not injeted into the sruer through the ypss lineF pigure PFIWX hemti desription of the gses injetion during evh proessD when hin is used s metl preursor nd r 2 y s n oxidntF hree gses @hinD x 2 yD nd x 2 A re onneted to the retor hmer y gs lines nd to the sruer y ypss gs linesF r 2 y gs line is only onneted to the retor hmerF fypss gs lines re used for the gs )ows stiliztionF he evh yle n e divided into four steps of injetion into retor hmerX hin injetion @step sAD hin purge y r 2 @step ssAD x 2 y injetion @step sssAD nd x 2 y purge y x 2 @step sAF golor rrows indite gs )ows @ville onlineAF x 2 y is injeted into the sruer through ypss line during ll evh proessF

x 2 y is injeted into the sruer through the ypss lineD hin nd r 2 y re not injeted t llF huring step sssD r 2 y is injeted into retor hmer @pigFPFIWD sssAF x 2 is injeted into the sruer through ypss lineD hin is not injeted t llF end during step sD x 2 is injeted inside the retor hmer for purging fter r 2 y pulse @pigF PFIWD sAF x 2 y is injeted into the sruer through ypss lineD the injetion of hin into ypss line is strted t time tat DEZn stabilization efore hin injetion into the retor hmer @step sAD r 2 y is not injeted t llF pigures fFP @see eppendix fA nd PFPH show vlues of proess prmeters meE sured during evh proess when hin is used s n preursorD wter s n oxidntD nd nitrogen @x 2 A s purging gsF he (gure fFP shows the ontrol sreenD on the 50 Chapter 2. MOON: An ALD/CVD reactor for in situ studies remote omputerD with pressuresD temperturesD )ow urves for severl evh ylesD mesured during evhF pigure PFPH shows typil vlues for one evh yleF es n e seen in the (gures fFP nd PFPHD x 2 y )ow is onstntD it is injeted into the sruer during ll evh proessD the vlue of x 2 y )owD regulted y x 2 y mss )ow ontroller @wpgAD is IHH smF pigure PFPHX ressuresD temperturesD )ow urves for one evh yleD mesured during evhF es it is shown in setion PFQFID r 2 y evportor pressure deresesD when r 2 y injetion into retor hmer strtsF henD when r 2 y injetion is stoppedD the pressure inside r 2 y evportor inreses gin due to the evportion of new r 2 y moleules from the r 2 y liquid phseF his typil derese nd inrese of wter evportor pressure re seen for eh evh yleF

x 2 )ow vlues re regulted y nitrogen wpgF xitrogen )ow during ll evh proess is IHHH smD exept eforeD during nd fter the hin injetion into the retor hmer @nitrogen )ow is set to PH smAF vow nitrogen )ow during the end of purging efore hin injetion is needed to reh quikly low pressure inside the retor hmerF e low retor pressure vlue @out I mrA gurnteesD tht hin will e injeted into the retor hmer when the ypss pressure p bypass is higher thn retor pressure p reactor @see susetion PFQFPFRAF ime is needed @<IsA for hin wpg to stilize the )ow vluesF es it is shown in pigF PFPHD the vlue of hin )ow is onstnt efore nd during hin injetion inE side evportor hmerF henD fter hin pulseD we stop hin injetion from the evportor y losing the pneumti vlve @see susetion PFQFPFQA nd ompletely open hin wpg for purging through ypss line @pigF PFIPAF e purge hin wpgD fter every hin pulse to sve the lifetime of hin wpg devieF vooking t the urve of hin )ow s funtion of timeD one n notie jump down of hin )ow @pigF PFPHD red ovl on the rightAD when hin wpg is opened fter hin pulseF he sustrte temperture is onstnt during evh proess @pigsF fFP nd PFPHAD nd it is osillting ner the sustrte temperture setpoint vlue due to the di'erent vlues of hinD r 2 yD nd x 2 )ows inside retor hmerF he mplitude of this osilltion is less thn I • gF fypss pressure p bypass strts inresing efore hin pulse @see susetion PFQFPFRAF henD during hin injetion into the retor hmerD hin is not inE jeted through the ypss lineD nd the ypss pressure strts to dereseF hen hin pulse is (nishedD hin wpg is ompletely opened for purgingD nd the hin residul gs from hin wpg re inreses ypss pressure gin @one n notie jump of pressureAF efter ypss pressure deresesD euse hin is not injetedD nd ypss line nd hin wpg re pumpedF he pressure inside retor hmer p reactor repets x 2 )ow trend @pigsF fFP nd PFPHAF yne n notie slight retor hmer pressure inrese during r 2 y injetion into the retor hmer @retor hmer is losedD when r 2 y is injetedAF 2.5 Conclusion sn this hpterD we showed the design nd operting priniples of the therml evh retor wyyx for the in situ experimentD developed t vwq lortory in ollE ortion with other lortoriesF efter retro(tting the retorD we instlled ypss gs lineD wter evportorD nd developed metl preursor evportion systemF sing ypss gs lines mkes it possile to hieve onstnt nd reproduile vlues of the )ows nd pressures of gses during evh proessF por injetion of the metlli preursorD we use n evportorD insted of ulerF sn omintion with mss )ow ontroller nd ypss gs lines of metl preursorD we n urtely ontrol the )ow nd pressure vlues of pure metl preursor gsD injeted into the retor hmerF his ensures ontrol of the ext mount of the injeted metl preursor during the pulseF es hs een shownD vrious oxidnts @x 2 y nd r 2 yA n e used during ny evh in the wyyx retorF sn ddition to existing nitrous oxide evportion systemD we instlled room temperture wter evportor with needle vlve llowing to hnge injeted wter )owF sn generl for wyyx retorD the entire evh proess is utomtedD nd ll pE rmeters re ontrolled y utomted equipmentF qeometri hrteristis of the retorD the presene of dedited windows nd )nge with tue for inserting n Ery )uoresene detetorD mkes it onvenient to perform in situ mesurements with Ery t synhrotron entersD s well s in the lortory y using optil methodsF yne of the min fetures of the wyyx retor is the presene of ounterErotting )ngeD whih llows to keep the retor (x while the smple heter is rotted y the di'rtometer tle round n xis perpendiulr to the smple surfeF his mkes it possile to rry out surfe di'rtion nd inEplne di'rE tion mesurements t synhrotron entersD this feture hs proved to e relevnt for qse too enud PHHWF es next step in retro(tting the wyyx retor n e the retion of heting system for the wter evportor whih would llow keeping onstnt temperture nd pressure inside the evportorF elsoD wter wpg n e instlled insted of needle vlve for preise ontrol of the )ow of injeted wterF he min results of mesurements otined during the evh proess with the wyyx retorD in prtiulrD monitoring of the ny growth on sn 0.53 q 0.47 es suE strtesD using Ery methodsD re presented in the following hptersF Chapter 3

Island growth modeling

In this chapter, I consider a simple geometric model of the growth of hemispheroidal shape islands for the simulation of ALD growth per cycle (GPC) curves. In the literature, islands growth mode is also referred as substrate inhibited growth of type 2, one of the possible transient regime before the steady growth is set. Assuming an island growth model, we show that the beginning of the experimental GPC curve can be tted by analytical function to extract some geometric parameters of islands. Then, these parameters are used for the simulation of the whole GPC curve, which repeats the shape of experimental GPC curve. The key parameters of the model are the steady state of growth GPC value (when the GPC versus number of cycles has become constant), density of the islands, and surface roughness. In the model, I consider the case of symmetrically located islands in the centers of the square grid cells. Thus, to calculate the average thickness and GPC as a function of the number of cycles, it is enough to consider one island, due to the symmetry of the system. The use of this model is a quick and easy way for the analysis of experimental GPC curves that show substrate inhibited growth of type 2, and simulation of average thickness, roughness, and growth per cycle (GPC) as a functions of the cycle number. ∆r: the inrementl inrese in thikness in the diretion prllel to the sustrte @n inrementl inrese of islnd se rdiusA ∆h: the inrementl inrese in thikness in the diretion perpendiulr to the sustrte @n inrementl inrese of islnd heightA r: the rdius of hemispheroidl islnd h: the height of hemispheroidl islnd µ: the verge thikness @or equivlent lyer thiknessA of islnds GPC(n): the growth per yle s funtion of yle numer n @qg@nA n e lulted y di'erentiting the verge thikness funtion µ(n)A n c : the yle numer t whih the islnds strt to olese @eginning of hse ssA N d : the islnd density R: the rdius of urvture of qg@nA funtion t point (n = 0, GP C(0))

GP C max : the vlue of the mximum of qg@nA funtion GP C nc : the vlue of qg@nA funtion t the point nan c ∆ GP C : qg pek height ove the plteu @ove the onstnt qg vlueA n shif t : simultion prmeter for shifting qg@nA funtion long the n xis α in.isl. : the spet rtio of the height of the initil islnd to the se rdius of the initil islnd

Introduction

etomi lyer deposition @evhA llows ontrolling the thikness of deposited mteril t the level of monolyersF he mount of deposited mteril nd growth per yle @qgA funtion depends on the retnts @preursorsAD the surfe t whih the retion tkes pleD nd the surfe temperture uurunen PHHSF husD qg t the initil stges of evh n e di'erent ompred to further growthD sine surfe hnge ours @the surfe of the deposited mteril is di'erent from the sustrte surfeAF pigure QFI shows four types of qg urves typil for evh initil stges uurunen PHHRF sf the mount of deposited mteril is onstnt t eh evh yleD then the growth is linerD nd the qg is onstnt funtion of yle numer @pigF QFI@AAF sf the growth in its initil stges is enhned y the sustrte surfeD the qg is high t the eginning of the growth then it levels down nd eomes onstnt @stedy regimeAD s shown in pigF QFI@AF elsoD the growth n e inhiited y the sustrte surfeF sf the qg inreses grdully to the stedy vlueD the growth is referred s sustrteEinhiited growth of type I @pigF QFI@AAF sf the qg rehes mximum nd then dereses to stedy vlueD this growth is referred s sustrteE inhiited growth of type P @pigF QFI@dAAF wodeling of sustrteEinhiited growth of type P reeived ttentionD severl models hve lredy een proposed elm PHHQD uurunen PHHRF qrowth modE eling nd trnsmission eletron mirosopy suggested islnd growth s n origin of sustrteEinhiited growth of type P uurunen PHHRF ustrteEinhiited evh pigure QFIX roposed lssi(tion for the evh proessesX @A liner growthD @A sustrteEenhned growthD @A sustrteEinhiited growth of type ID nd @dA sustrteEinhiited growth of type P from efF uurunen PHHRF growth of type P hs previously een nlyzed using di'erent phenomenologil models uurunen PHHRF imultions of islnd growth y wonte grlo tehniques hve lso een demonstrted for morphous xilsen PHHU nd polyrystlline growth shows tht it is possile to reprodue sustrteEinhiited growth ehvior of type PD just using onstnt ojetEinherent growth rte of hosen geometril ojet s islndF hen simulting growth with geometri ojetsD the pertinent growth prmeE ters re the surfe re for the growth to tke pleD the shpe of this surfeD nd the lws whih govern the surfe nd volume of the ojets t eh evh yleF st ws previously shown xilsen PHHUD tht the thiknessD growth rteD nd roughness versus yle numer depend on the initil shpe nd re of the surfe ville for deposition nd the positions nd shpe of initil islnds @nuleusAF yne importnt prt of my work hs een devoted to the development of qunE tittiveD phenomenologil islnd growth model to extrt relevnt prmeters from experimentl qg urves depending on the growth onditionsF he model is sed on n nlytil model used to desrie islnd growth y geometril priniples xilsen PHHUF sn our modelD we hve used hemispheroidl or hemispheril islndsF he ltter orresponds to prtiulr se when the islnd se rdius to islnd height rtio @islnd spet rtioA is equl to IF fy hnging the spet rtioD we hnge the initil shpe of the nuleus @shpe of initil islndAD nd therefore the ehvior of growth rte funtion vs yle numerF yur gol hs een to (nd simple model tht would llow to understnd nd eventully reprodue the experimentl growth rte urvesF feside islnds sed numeril simultionsD we hve worked out nlytil funtions whih n e used to nlyze experimentl dt nd otin strting prmeters for simultion of the dtF rereD we onsider ordered ojets on the surfeF por loseEpking of hemispheres with the sme rdius on surfeD their enters should e pled on the nodes of twoEdimensionl hexgonl lttieF st ws shown xilsen PHHU tht the initil lotion of the islnds 'ets the shpe of the growth per yle @qgA funtionF hue to the totl surfe re hngeD whih depends on the position nd size of identil hemispheril islndsD the shpe of the qg urve mximum is di'erent for the ses when islnds pled t rndom or in di'erent orderly mnner @for the sme density of islnds on the surfeAF sn this hpterD we onsider the simplest se when the enters of the geometri ojets re pled t the enters of squre ells of twoEdimensionl squre lttieF e (rst onsider the se of hemispheril islnds nd the e'et of the islnd9s geometri prmeters on the shpe of qg urveF henD we show tht the use of hemispheroidl islnds insted of hemispheril islnds mkes it possile to hnge the initil surfe roughnessD whih 'ets the height of the qg urve mximumF 3.2 Hemispheroidal islands model sn our modelD we onstrut squre lttieD eh squre with side length of bF e then ple identil nulei t the enters of ll the squresF eordinglyD the nerest distne etween two nulei enters is bF his implies tht when the dimeter of eh hemispheroidl islnd is bD the islnds strt to oleseF e rossEsetion of n 3.2. Hemispheroidal islands model 57 islnd is shown in pigF QFQF pigure QFQX qeometril prmeters of the spheroidl islnd used in our islnd growth modelY r 0 nd h 0 de(ne the size of the nuleusD b is the distne in etween P nuleiD ∆r nd ∆h re the inrementl inrese in thikness in the diretions prllel nd perpendiulr to the sustrteD respetivelyD t eh evh yle @i.e. the qgAF e de(ne r nd h s the se rdius nd height of the hemispheriod @islndAD respetivelyF sf the rtio h/r is ID the hemispheroid is hemisphereF e ssume tht the rdius r nd height h inrese y the vlues ∆r nd ∆hD respetivelyD t eh evh yleF herefore r = r 0 + (n -1)∆r,

h = h 0 + (n -1)∆h, @QFIA
where n is the numer of evh yleF his eqution is vlid when n 1 euse we ssume tht initil hemispheroidl islnd nulei with se rdius r 0 nd height h 0 hve ppered fter the (rst evh yleF e previous work uurunen PHHR distinguishes three growth phses depending on the rtio etween the rdius of the islnd se rD nd the distne etween the islndsD bD s shown in pigF QFRF Phase I orresponds to the growth of isolted islnds @r < b/2A where the islnds re well seprted nd not touhing eh otherF es the rdius r inreses nd rehes the vlue r = b/2D eh islnd touhes its four nerest neighor islndsF Phase II orresponds to islnd olesene when the rdius r vries in the rnge b/2 r < b/ √ 2F huring phse ssD the islnds ontinue to olese until they ompletely over the surfeF his orresponds to the eginning of Phase IIID where r b/

√

2F he verge thikness µ @or equivlent lyer thiknessA of islnds hving the funtionl shpe z island (x, y) nd lolized within region D is de(ned s xilsen PHHU pigure QFRX sslnd growth phsesX @A isolted islnd growthD @A nd @A islnd olesene nd @dA ontinuous islnds @Ph lyerAF

µ = D z island (x, y)dxdy D dxdy , @QFPA
where x nd y re inEplne oordintesF por the se of n isolted islnd with volume V (n)D loted in squre of re b × bD the verge thikness is

µ(n) = V (n) b 2 . @QFQA
hen knowing the funtionl shpe of surfe overed with islndsD z(x, y)D the w n e lulted t ny yle s followsX

RM S =       D (z(x, y) -µ) 2 dxdy D dxdy       1/2 .
@QFRA e therefore distinguish four prmeters 'eting the growth of islndsX r 0 [nm]D h 0 [nm] ! initil islnd se rdius nd height lredy de(ned oveD ∆r[nm] nd ∆h[nm] ! the inrementl inrese in rdius nd height per growth yleD nd b[nm] ! the verge distne etween the enters of the nerest neighor islndsF rerefter we desrie the qulittive e'ets of these prmeters on growth per yle @qgAF qg@nA funtion n e lulted y di'erentiting the verge thikE ness funtion µ(n)X GP C(n) = dµ(n) dn . @QFSA 3.3. Simulation algorithm using hemispheroidal islands 59 3.3 Simulation algorithm using hemispheroidal islands he verge thikness nd qg n e simulted using hemispheroidl islnd model proposed in setion QFPF hue to the trnsltion symmetry of the squre gridD the verge thikness µ nd qg determined y one islnd pled in the enter of squre of size b × b re the sme s µ nd qg lulted for group of identil islnds pled in the enters of the squre grid ellsF husD for lultion of µ nd qgD it is resonle to onsider just the se of one hemispheroidl islnd @or even it is possile to onsider the se of 1/4 of n islndD due to the fourEfold symmetry of squre lttieAF o lulte the qg for evh yle nD we hve to know the verge thikness µ for yles n nd (n -1)F he verge thikness of hemispheroidl islndD pled in squre b × b ellD n e otined numerilly if we know the shpe of the islndF pigure QFS shows n exmple of simultion of n hemispheroidl islnd with identil squre se pillrs of di'erent heights @xz nd xy plne rossEsetionsAF es pigure QFSX en exmple of hemispheroidl islnd @orngeA in squre b×b @light greenA nd prmeters used for simultionF he xis xD yD nd z xis interset in enter of islnd seF he xis x nd y re in the plne of islnd se @see lower (gureAD z xis is perpendiulr to the islnd se plne @see top (gureAF he squre b × b limits the islndF imultion lgorithm hek ll the points @x i D y j A in the mtrix i × jD where row i nd olumn j vlues hnge from I to N F por the hosen yle nD the (z ij ) n vlue of squres with enters pled inside islnd se irle @(x i ) 2 n + (y j ) 2 n r 2 n A for hosen yle n is determined y eqution QFV @ornge squres nd linesAF shown in (gure QFSD we divide the ell into N 2 squresD tht form n N × N mtrix of squresF he sides of the squres ∆x nd ∆y re prllel to the x nd y xis re de(ned sX

∆x = ∆y = b N . @QFTA
ih squre in the N × N mtrix is identi(ed y two numersD i nd jF ht de(ne the position @iD jA of the squre in x nd y diretionF end the x i nd y j re oordintes of the enter of ∆x × ∆y suEell @iD jA inside b × b ellF e ple the enter of the suEell @1D 1A t the point @-b/2 + (∆x)/2D -b/2 + (∆x)/2AF henD for suEell @N D N AD the oordintes re @b/2 -(∆x)/2D b/2 -(∆x)/2AF sn the generl seD the oordintes of suEell enter @x i D y j A n e writtenX

x i = - b 2 + ∆x 2 + ∆x × (i -1), i = 1, 2, .. , N ; y j = - b 2 + ∆x 2 + ∆x × (j -1), j = 1, 2, .. , N.
@QFUA hen the oordintes x i nd y j re givenD we n lulte z ij oordinteD using the eqution of spheroid

x 2 r 2 + y 2 r 2 + z 2 h 2 = 1
F sn the se of hemispheroidl islndD we use the spheroid eqution for z 0D where r nd h re the se rdius nd height of the hemispheroid @iqF QFIAF por evh yle nD the rdius of hemispheroidl islnd se @diskA r n limits the numer of points with oordintes (x i ) n nd (y j ) n F henD provided tht (x i ) 2 n + (y j ) 2 n r 2 n D the z ij oordinte for yle n n e found using the spheroid equtionX

(z ij ) n = h n r n r 2 n -(x i ) 2 n -(y j ) 2 n .
@QFVA por the points @x i D y j AD whih do not stisfy the eqution ondition @(x i ) 2 n + (y j ) 2 n r 2 n AD z ij is zeroF e n notie tht ll z ij oordintes hve nonEzero vlues when r n b/ √ 2 @ontinuous islnds @Phase IIIAD see pigF QFR@dAAF por simultionD we rewrite the verge thikness in iqF QFPD repling the integrl y sumF end then using the de(nition of ∆x @eqF QFTAD the verge thikness µ t yle n n e written sX

µ n = N i=1 N j=1 (∆x) 2 (z ij ) n b 2 = 1 N 2 N i=1 N j=1 (z ij ) n . @QFWA ixpression QFR for roughness n e rewrittenX RM S n = 1 b   N i=1 N j=1 ((z ij ) n -µ n ) 2   1/2
. @QFIHA 3.3. Simulation algorithm using hemispheroidal islands 61 hen the verge thikness µ n s funtion of yle numer n is knownD GP C n n e lulted s

GP C n = µ n -µ n-1 . @QFIIA
pigure QFT shows n exmple of simulted qg urve otined y using hemispherE il islnd modelD whih orresponds to n islnd spet rtio h/r equl to 1D nd ∆r = ∆hF he qg urve exhiits hrteristi mximumD it orresponds to the pigure QFTX en exmple of simulted qg urve otined y using hemispheril islnd modelD whih orresponds to n islnd spet rtio h/r equl to 1D nd ∆r = ∆hF GP C max orresponds to point where the qg rehes mximumY GP C nc is vlue of qg t the eginning of islnd olesene when r = b/2 nd n = n c @see pigF QFR@AAF qg urve tends to ∆h @dshed lue lineAY ∆ GP C is qg pek high ove ∆hF yle numer for whih the surfe re of the (lm rehes mximum efore the eginning of the next yleF wost generllyD the yle numer of the pek mximum depends on the verge distne etween enters of the nerest neighor islndsD bD on the initil size of the nulei @r 0 D h 0 AD nd inrementl vlues ∆r nd ∆hF huring hse sssD s the rdius of the islnds ontinues to inrese @pigF QFR@dAAD the surE fe eomes smooth on vergeF st n e seen in (gure QFT tht the qg funtion tends to vlue ∆h = ∆rX

lim n→∞ h r = lim n→∞ h 0 + n∆r r 0 + n∆r = 1. @QFIPA
elsoD we n notie tht the points of qg urve orresponding to the eginning of olesene @GP C nc A nd the mximum of qg @GP C max A re not the smeD ut very loseF es for islnd growth modeD the mximum of qg is ove the qg plteu vlue orresponding to stedy liner growthY we de(ne the di'erene etween GP C max nd @∆h = ∆rA s ∆GP C @see pigF QFTAF 3.4 Analysis of GPC functions using the model of hemispherical islands rerefterD we onsider the se when the islnd rdius inrementl inrese for one evh yle is onstnt for eh yle nd for ny growth diretionF his orresponds to the se when ∆r = ∆hF elsoD for the lultions we tke the initil nuleus rdius nd height vlues equl to ∆r @r 0 = h 0 = ∆rAF henD equtions QFI n e written sX r = n∆r; h = n∆r. @QFIQA pigure QFR@A shows tht when olesene strtsD the islnd rdius is r = b/2F henD using eqution QFIQ the verge distne etween the enters of hemispheril islnds b n e lulted sX b = 2∆r

• n c , @QFIRA
where n c is the yle numer t whih the islnds strt to olese @pigF QFR@AAF ine one squre ell ontins one islndD the islnd density x d n e lulted sX

N d = 1 b 2 . @QFISA
o nlyze experimentl qg urvesD we n nlytilly lulte the qg dependene in Phase ID for instneD in the se of hemispheril islndsF he volume of hemispheril islnd is funtion of islnd rdius rX V hemisphere = 2 3 πr 3 . @QFITA sing equtions QFQD QFIQD QFIRD nd QFIT we write the verge thikness s ui funtion of the numer of ylesX

µ(n) = 2 3 πn 3 (∆r) 3 1 4(∆r) 2 n 2 c = π 6 ∆r n 2 c n 3 . @QFIUA he (rst derivtive of µ(n) is the GP C(n) funtionX GP C P hase I (n) = π 2 ∆r n 2 c n 2 . @QFIVA st is knownD tht the rdius of urvture R of prol y(x) = a 1 • x 2 t point @x = 0Dy = 0A is R = 1/(2a 1 )F henD funtion QFIV n e written s GP C P hase I (n) = 1 2R n 2 , @QFIWA
where RD the rdius of urvture t point

(n = 0, GP C(0)) is given yX R = n 2 c π∆r . @QFPHA
purtherD in the textD we onsider di'erent ses of qg urve ehvior when one of the three vriles in expression QFPH @RD ∆rD or n c A is onstntD nd the two others re not onstntF 3.4. Analysis of GPC functions using the model of hemispherical islands 63 3.4.1 Radius of curvature is constant hen the rdius of urvture R of the proli qg funtion in Phase I is onstntD ∆r = ∆h nd n c re onneted yX

∆r = 1 πR × n 2 c . @QFPIA gomining equtions QFIR nd QFPID it n e seen tht b is ui funtion of n c X b = 2∆rn c = 2 n 2 c πR n c = 2 πR × n 3 c . @QFPPA
sn Phase ID if the rdius of urvture R is onstntD ∆h = ∆r inreses s n c squredF e onsider for exmple the se where R = (2/π) • 10 3 cy 3 .nm -1 @we denote symolilly cycle s cyAD nd simulte series of qg urves for di'erent n c = 17, 18, .., 23 cy @pigF QFUAF por omprisonD prol with the sme rdius of urvture is lso plotted @pink lineA in (gF QFUF gompring qg urves for pigure QFUX en exmple of di'erent qg urves simultion when the rdius of urvture of qg urve is (xed @eqution QFPHA in hse sF por R = (2/π) × 10 3 cy 3 .nm -1 D the numer of yles when the islnd olesene strts is vried @n c = 17, 18, .., 23AF hen n c inreses linerly @vertil gry dotted line is shifted to the higher yle numersAD the plteu vlue of qg urve in hse sss inreses s n 2 c F he limit of qg funtions @∆h = ∆rD lue dotted lineA is shifted upwrds to higher qgsF e prol with the sme rdius of urvture @pink lineA is plotted for omprisonF inresing n c D we n notie tht the mximum of qg urve is shifted towrd higher vlues of the yle numerD nd the qg funtion in Phase III inreses s n c squredF his qg inrese is explined y the ft tht qg@nA funtion vlue when n eomes lrge is ∆h = ∆rD ∆r inresing s qudrti funtion of n c F pigure QFU shows tht the vlue of the mximum of qg @GP C max A nd qg@n c A inrese with inresing n c F eording to eqution QFIVD the qg for n = n c @we denote it s qg nc A when islnd olesene strts isX

GP C nc = GP C P hase I (n c ) = 1 2R n 2 c . @QFPQA
rovided tht the GP C max nd GP C nc vlues re pproximtely equlD qg pek height ove the plteuD denoted s ∆ GP C @pigF QFTAD n e lulted s the di'erene etween GP C nc nd the limit vlue of the qg plteuD ∆rF hen

∆ GP C s funtion of n c is di'erene etween GP C nc nd ∆r s funtions of n c X ∆ GP C (n c ) = GP C max (n c ) -∆r(n c ) = 1 2R n 2 c - 1 πR n 2 c = π -2 2πR n 2 c . @QFPRA ∆ GP C (n c ) nd GP C nc (n c ) re oth qudrti funtions of n c D ut with di'erent onstnt ftors @∆ GP C (n c ) = ((π -2)/π)) GP C nc (n c )AF pigure QFV@A
GP C nc (∆r) = π 2 ∆r n 2 c n 2 c = π 2 ∆r, ∆ GP C (∆r) = GP C nc (∆r) -∆r = π 2 -1 ∆r, @QFPSA
∆ GP C (∆r) nd GP C nc (∆r) re liner funtions of ∆rD ut with di'erent onstnt ftorsD @π/2 -1A nd @π/2AD respetivelyF pigure QFV@A shows lulted vlues of ∆ GP C nd GP C nc s funtion of ∆r for (xed R = (2/π) • 10 3 cy 3 .nm -1 F snside gry retngles in (gure QFV@A re shown ∆ GP C nd GP C nc vlues for the sme ∆r vlues s those of the urves shown in (gure QFUF 3.4. Analysis of GPC functions using the model of hemispherical islands 65 3.4.2 n c is constant e onsider the se when n c is onstntF henD R(∆r) is inversely proportionl to the ∆h = ∆r rgument nd b(∆r) is liner funtion of ∆rX

R(∆r) = n 2 c π × 1 ∆r , @QFPTA b(∆r) = 2n c × ∆r. @QFPUA
pigure QFW shows series of qg urves for di'erent ∆r @∆r = 0.17, 0.18, .., 0.23D for exmpleA when n c is (xed @n c = 20D for exmpleAF yne n notie tht for lrger pigure QFWX en exmple of di'erent qg urves simultion when the n c @eqution QFPHA is (xedF por n c = 20D the inrementl inrese ∆h = ∆r ws vried @∆r = 0.17nm, 0.18nm, .., 0.23nmAF hen ∆r is inresed linerly @light lue short dot line is shifted to the re of higher qgsAD the slope of qg funtion t hse s nd b vlue @pigure QFV@AA grow proportionlly to the liner funtion of ∆rF ∆r the qg plteu hs leveled upF gompring equtions QFPT nd QFPUD we n see tht for for lrger ∆r = ∆hD b is lrger nd rdius of urvture R is smllerF es ws shown in the previous susetionD the GP C nc nd ∆ GP C re liner funtions of ∆r with oe0ients (π/2) nd (π/2 -1) respetively @eqution QFPSAF GP C nc nd ∆ GP C re oth inversely proportionl to the R rgumentD ut they hve di'erent onstnt oe0ients @∆ GP C

(R) = ((π -2)/π) × GP C nc (R)AX GP C nc (R) = n 2 c 2 × 1 R , ∆ GP C (R) = (π -2)n 2 c 2π × 1 R . @QFPVA

Example of t with hemispherical-island model

rereD we show tht it is possile to simulte qg urve using hemispherilEislnd model @when ∆h = ∆rAF es demonstrted in previous setionsD knowing the 1/R of 3.4. Analysis of GPC functions using the model of hemispherical islands 67 qg funtion in Phase I @n < n c AD we know how n c nd ∆r re onnetedF pigure QFII shows n exmple of experimentl qg urve of sustrte inhiited growth of type P @the detils of experiment nd extrtion of this qg urve re given in the etion RFR of ghpter RF vet9s show n exmple of qg urve (tting using this pigure QFIIX ixmple of the (t of experimentl qg urve @lue pointsA using hemispheril islnd modelF he region for the (t on hse s @pigure QFR@AA is loted in etween two gry linesF iqution QFQI ws used to (nd the Slope nd n shif t vlues y (tting qgF experimentl dt nd hemispheril islnds modelF pirstD we (t dt in the hse s region @orresponding to the growth of isolted islndsAF por this we hoose the points whih re in the region of Phase I @in pigure QFII those points re in etween the two vertil gry linesAF he points in this region n e (tted with expression QFIWD ut here we use n dditionl prmeter n shif t for shifting the prol long the n xisF he prmeter n shif t is used to determine yle numer when the islnd growth strtedD for the se if it is needed to pss severl evh yles to strt inresing qgF henD eqution QFIW is rewrittenX

GP C P hase I (n) = 1 2R (n -n shif t ) 2 , @QFQIA
where n shif t is n n vlue where qg is equl to zeroF fy (tting funtion QFQI to the experimentl dtD we (nd the vlues of R nd n shif t D whih re used for qg urve simultionF es shown oveD for (xed vlue of RD there re in(nite numer of n c nd ∆r vlues onneted y eqution QFPHF ∆r n e otined from the experimentl dtF sn the se when the experimentl qg shows plteu @qg t the stedy stge of growthD liner growthAD we n use the verge qg vlue t the plteu s ∆r vlueD euse in the present hemispheril islnd model qg urve tends to ∆r for lrge nF henD knowing ∆r from experimentl qg urveD we n lulte n c F 68 Chapter 3. Island growth modeling sn seD when experimentl qg urve did not reh plteu @for instneD the numer of evh yles in experiment ws not high enough to reh onstnt qgAD n c n e extrted s yle numer when the (rst derivtive of qg strts to derese @in)etion pointAF ht point orresponds to the yle numer where Phase I is (nished @n = n c AF end thenD knowing n c D ∆r n e lultedF hen ∆r nd n c re determinedD one n esily lulte b @iqF QFIRAF por the qg urve simultion with the islnd modelD we use prmeters whih were foundX r 0 = h 0 = ∆r = ∆h nd bF e notie tht for the se of hemispheril islnd modelD the islnd spet rtio h/r stys equl to IF end (nllyD for the numeril simultion of the hole qg urve we need just two prmetersX ∆r nd b @or islnd density N d = 1/b 2 AF roweverD using simple hemispherilEislnd model sometimes pek height ∆ GP C of simulted qg urve n e di'erent from pek height of experimentl qg urveF yne of the solutions of this prolem is to use hemispheroidlEislnd model whih llows the spet rtio of n initil islnd to e t vlue di'erent of oneF his prolem is onsidered in the next setionF 3.5 Initial surface RMS eect on GPC shape sn this setionD we onsider the se of hemispheril shpe islnd with (xed initil spet rtio h/r for given numer of yle or given qg vlueD nd for ∆r = ∆hF ghnging the h/r spet rtio of n initil islndD nd ordinglyD the islnd shpeD surfe re nd ordingly qg funtion hngeF sn this seD setting the rtio of the initil islnd plys the role of setting the initil surfe roughnessF e n give n nlytil eqution for qg funtion in Phase IF he volume of hemispheroid isX

V h.spheroid = 2 3 πr 2 h.
@QFQPA e de(ne for yle n in.isl. D the se rdius r in.isl. D the height h in.isl. of the islndD nd respetively the spet rtio α in.isl. = h in.isl. /r in.isl. F henD for eh next yleD we inrese the se rdius nd the height y ∆h = ∆rF hen n n in.isl. D the expression for r nd hD n e written s

r(n) = r in.isl. + (n -n in.isl. )∆r, h(n) = h in.isl. + (n -n in.isl. )∆r. @QFQQA hen if n in.isl. is 1D r = r in.isl nd h = h in.
isl F ixpression QFQQ is written for n n in.isl. D nd n in.isl. > 0 euse islnd rdius r nd height h for yle H @evh hs not een strtedA should e equl to HF rereD to hve the ility to ompre di'erent simulted qg urvesD we deterE mine r in.isl. s @n in.isl. ∆rAD where n in.isl. is the numer of yles needed to reh islnd se rdius r in.isl. F e de(ne n in.isl. s onventionl vlueD it is hosen just to determine r in.isl. nd it ould e not n integerF henD for qg urve simulE tionD the numer of yles n is lso reltive vlueF he numer of yles n sim. in.isl.

nd n exp.

in.isl. of simulted nd experimentl qg whih orresponds to the initil islnd qg @GP C in.isl. A n e di'erentF henD the point of simulted qg urve (n sim. in.isl. , GP C in.isl. ) hve to e shifted long the xis of yle numer to the point with oordintes (n exp. in.isl. , GP C in.isl. )F gonsidering tht r in.isl. = n in.isl. ∆r nd ∆h in.isl. = α in.isl. ∆rD we rewrite equE tion QFQQX

r = n∆r, h = α in.isl. n in.isl. ∆r + (n -n in.isl. )∆r = (n in.isl. (α in.isl. -1) + n)∆r.
@QFQRA henD using equtions QFQP nd QFQRD the volume of hemispheroidl islnd isX

V h.sheroid (n) = 2 3 π(n∆r) 2 (n in.isl. (α in.isl. -1) + n)∆r = = 2 3 π(∆r) 3 n 2 (n in.isl. (α in.isl. -1) + n).
@QFQSA king in ount tht b = 2 • ∆r • n c nd using eqution QFQD we n write the verge thikness funtion for hemispheroidl islnds in Phase IX

µ h.sheroid (n) = π 6 ∆r n 2 c n 2 (n in.isl. (α in.isl. -1) + n). @QFQTA qg funtion for Phase I is the (rst derivtive of µ h.sheroid (n)X GP C h.sheroid (n) = dµ h.sheroid (n) dn = = π 6 ∆r n 2 c (2n(n in.isl. (α in.isl. -1) + n) + n 2 ) = = π 6 ∆r n 2 c (3n 2 + 2n in.isl. (α in.isl. -1)n).
@QFQUA sing hemispheroidl islnd modelD we hve simulted series of qg urvesF pigure QFIP @A shows qg urves for di'erent spet rtios of initil islndsD α in.isl. = 0.4, 0.6, .., 1.6Y when ll other prmeters re (xed @n in.isl. = 10D n c = 20D nd ∆r = 0.2nmAF e n notie tht the initil GP C in.isl. vlue inreses with inresing spet rtios α in.isl. F st is euse initil islnds hve the sme se rdiusD ut di'erent height h depending on the spet rtio αD for the lrger α the islnd surfe is lrgerD nd thereforeD the qg vlue t n = n in.isl. is lrgerF he GP C in.isl. n e lulted using eqF QFQUX

GP C in.isl. = GP C hemisheroid (n in.isl. ) = = π 6 ∆r n 2 c (3n 2 in.isl. + 2n 2 in.isl. (α in.isl. -1)) = = π 6 ∆r n 2 c n 2 in.isl. (1 + 2α in.isl. ).
@QFQVA pigure QFIPX @A qg urves for di'erent spet rtios of the initil islnd α in.isl. = 0.4, 0.6, .., 1.6D the other prmeters re (xed @n in.isl. = 10D n c = 20D nd ∆r = 0.2nmAF he initil GP C in.isl. vlue inreses with inresing spet rtios α in.isl. F @A espet rtios h/r s funtion of yle numer orresponding to the di'erent qg urves shown in @AF ssoEqg lines re represented on oth @A qg nd @A spet rtio urves @dotted linesAF golors @olor rA indite di'erent qg vluesF @A hemti representtion of islnds with di'erent spet rtio with the sme islnd seF por qg urve simultionD the vlue of GP C in.isl. n e hosenF he hosen qg in.isl. vlue determines the yle numer from whih the qg funtion is simE ultedF sf GP C in.isl. is (xedD it is esy to solve the inverse prolem nd (nd n in.isl. y using eqution QFQVX

n in.isl. = 6n 2 c GP C in.isl. π(∆r)(1 + 2α in.isl. )
. @QFQWA henD if GP C in.isl D ∆rD nd n c re givenD we n simulte qg urve for di'erent α in.isl. F pigure QFIQ shows series of qg urves simulted for di'erent spet rtios of the initil islnd @α in.isl. = 0.4, 0.6, .., 1.6A when GP C in.isl. = 0.05nmD ∆r = 0.2nmD nd n c = 20 re (xedF sf we shift ll these qg urves long the nExis y n in.isl. D it is possile to ompre di'erent simulted urves otined for di'erent α in.isl. qg nd sme qg in.isl. plotted from the sme strting point @n = n in.isl. AF pigure QFIR shows the sme qg urves like in (gure QFIQD ut insted numer of yle n xesD numer of yles n minus n in.isl. xis ws usedF hue to the shift of ll the point of qg urveD n c lso is shiftedF ivery qg urve for given α hd pigure QFIQX @A he series of qg urves simulted for di'erent spet rtios of the initil islnd @α in.isl. = 0.4, 0.6, .., 1.6A when GP C in.isl. = 0.05nmD ∆r = 0.2nmD nd n c = 20 re (xedY nd @A is there islnds spet rtios h/r s funtion of yle numerF hi'erent short dot lines orrespond to the points of qg @A or spet rtio @A urves @isoEqgD or equiEqg linesA when every point of this line hs the sme qg vlueF golors @olor rA shows di'erent qg vlues of isoqg linesF @A hemti representtion of islnds with di'erent spet rtio nd the sme islnd surfe @or sme initil qgAF its own vlue of n c F he n c for this se n e determined using equtions QFQV nd QFQWF pigure QFIR shows tht inresing h/r spet rtio for the initil islnd for whih the qg vlue is (xedD the height of the mximum over the plteu of the qg funtion inresesF he simultion method imittes the initil roughness inrese y inresing h/r spet rtioF he initil roughness in)uene on the qg pek height ws lredy demonstrted in the efF xilsen PHHUF o simulte experimentl qgD we perform the following stepsF pirstD we deterE mine ∆h = ∆r y (tting the plteu stedy stte growth region of the qg urve y onstnt funtion or y using hemispheril islnd modelF sf it is not possile to determine ∆h = ∆rD it is then free prmeter for our simultionF henD we hoose GP C in.isl. for our simultionF st orresponds to the vlue of experimentl qg where the simultion eginsF henD for this given initil islnd qg vlue GP C in.isl. we lulte the spet rtio α in.isl. @it is shown elowAF prom experimentl qg we n hoose GP C nc @or GP C max D if we ssume tht pigure QFIRX @A shifted qg urves @(gF QFIQA long the xis of the numer of yles n on n in.isl. to ompre di'erent qg simultions plotted from the sme point for di'erent α in.isl. Y nd @A is there shifted spet rtios h/r long the xis of the numer of yles n on n in.isl. F hi'erent short dot lines orrespond to the points of qg @A or spet rtio @A urves @isoEqgD or equiEqg linesA when every point of this line hs the sme qg vlueF golors @olor rA shows di'erent qg vlues of isoqg linesF GP C max ≈ GP C nc AF GP C nc n lso e lulted using equtions QFQU nd QFQWX

GP C nc = GP C hemisheroid (n c ) = π 6 ∆r n 2 c (3n 2 c + 2n in.isl. (α in.isl. -1)n c ) = = π 6 ∆r n 2 c   3n 2 c + 2 6n 2 c GP C in.isl. π(∆r)(1 + 2α in.isl. ) (α in.isl. -1)n c   = = π 6 (∆r) 3 + 2 6GP C in.isl. π(∆r)(1 + 2α in.isl. ) (α in.isl. -1) = = π 6 (∆r)   3 + 2 6GP C in.isl. π(∆r) (α in.isl. -1) 2 (1 + 2α in.isl. )   . @QFRHA
hen GP C nc is known from experimentl qg urveD we n (nd α in.isl. from eqution QFRHX

GP C nc = π 6 (∆r)   3 + 2 6GP C in.isl. π(∆r) (α in.isl. -1) 2 (1 + 2α in.isl. )   , (α in.isl. -1) 2 (1 + 2α in.isl. ) = (GP C nc - π 2 (∆r)) π∆r 2GP C in.isl. 3π (∆r)
. @QFRIA 3.6. Conclusion 73 he rightEhnd side of the lower eqution QFRI is onstntD we denote it y √ c 1 X

c 1 =     (GP C hemisheroid (n c ) - π 2 (∆r)) π∆r 2GP C in.isl. 3π(∆r)     2 . @QFRPA he eqution QFRI is qudrti with funtion rgument α in.isl. X (α in.isl. -1) 2 (1 + 2α in.isl. ) = c 1 , α 2 in.isl. -2(1 + c 1 ) • α in.isl. + (1 -c 1 ) = 0.
@QFRQA he solution of this eqution is the funtionX

α in.isl. 1, 2 = (1 + c 1 ) ± c 1 (3 + c 1 ), @QFRRA
espet rtio α is positiveD thus we should hoose the positive rootF e showed tht when bD ∆h = ∆r re knownD using vlue of the mximum of qg urve GP C max ≈ GP C nc nd hoosing vlue GP C in.isl. D we n determine α in.isl. @equE tions QFRP nd QFRRAF henD we n use prmeters bD ∆h = ∆rD α in.isl. D nd n in.isl. @see eqution QFQWA for qg urve simultionF

Conclusion

sn this hpterD we hve showed the in)uene of islnd geometry on the shpe of qg urves efore the stedy growth is set @trnsient regime of growthAF por simultion of the verge thiknessD qgD nd roughness s funtion of yle numerD we used geometri model of the growth of hemispheroidl islnds loted in the enter of squre grid @or lttieA ellsF henD due to the trnsltion symmetry of the islnd positionsD the verge thiknessD qgD nd roughness re lulted for one islnd pled in squre ellF he proposed model mkes it possile to simulte oth isotropi nd nisotropi hemispheroidl islnd growth depending on the rtio of the islnd height inrementl inrese ∆h to islnd se rdius inrementl inrese ∆rF e hve onsidered the prtiulr se when growth is isotropi @∆h = ∆rAF e hve shown tht in the se of hemispheril islndsD it is possile to lulte nlytilly the qg funtion in the region efore the olesene of islnds @Phase IAF sn tht regionD qudrti funtion is usedF prom the (tD one reovers the rdius of urvture of the qg qudrti funtionD whih is relted to the inrementl inrese of the rdius of hemispheril islnd ∆h = ∆r nd the islnd density N d F ine the vlue ∆h = ∆r is equl to the vlue of the qg in the stedy stte of growth regionD it n e otined y (tting the orresponding plteu of the experimentl qg urveF henD knowing ∆r = ∆h nd vluesD n islnd density x d n e lultedF hese prmeters re used for qg urve simultionF e showed tht the pek height of the qg funtion ove the qg plteu @stedy growthA n e hnged y hnging the initil surfe roughness @initil islnd spet rtioA t given yle numer or for the seleted funtion vlue on Phase IF rying the initil roughnessD it is possile to hieve the sme qg pek height ove the plteu for simulted qg funtion s for experimentl qg funtionF husD simple model for the growth of hemispheroidl islnds n e used for qg urve simultion nd extrtion of islnd prmetersF sn the se when wellEseprted islnds re not oserved experimentlly uurunen PHHSD nd the sustrte inhiited growth type ss is used y surfe roughness hngeD the proposed model n lso e used for simulting the verge thiknessD qg nd the roughness s funtion of yles numerF Chapter 4

Synchrotron in situ studies, part I (SIRIUS-SOLEIL)

In this chapter, a complementary suite of in situ synchrotron X-ray techniques (uorescence, reectivity and absorption) as well as modeling is used to investigate both structural and chemical evolution during the initial growth of ZnO by atomic layer deposition (ALD) on In 0.53 Ga 0.47 As substrates. The study was carried out with the MOON reactor described in Chapter 2. We evidence a transient regime that takes place prior to the steady-state of growth, which is characterized by two stages. First, a substrate-inhibited ZnO growth takes place on InGaAs terraces. This leads eventually to the formation of a 1-nm-thick, two-dimensional (2D) amorphous layer. Second, the growth behavior and its modeling suggest the occurrence of dense island formation (see Chapter 3, with an aspect ratio and surface roughness that depends sensitively on the growth condition). Finally, ZnO ALD on In 0.53 Ga 0.47 As is characterized by a steady-state of growth ("layer-by-layer") with a constant growth rate equal to 0.21 nm.cy -1 , as expected for layer-by-layer ZnO ALD.

Introduction

etomi lyer depositionD ylil deposition proess sed on selfEterminting hemil retionsD is n idel synthesis tehnique for the growth of inorgni mteE rils in the nnometer thikness rngeF huring stedy growthD eh retnt speies sturtes nd dsors to the growing surfe suh tht the thikness per yle is often lose to one monolyerF roweverD there n e onsiderle vriility in the initil stgesD when surfe sturtion depends on the steri hindrne of the reE tnt lignds nd the rel density of retive sites uurunen PHHSF he existene of fewer retive sites on the sustrte dereses the mount of deposited mteril per yle nd leds to the formtion of Qh islndsF his sustrteEinhiited growth ehvior uurunen PHHR is typilly oserved for deposition on highly dissimilr mterils uurunen PHHRD fji PHIPD ilm PHHID uim PHIHD vim PHHHD tt PHHPD qreen PHHPD resulting in trnsient regime prior to the onset of stedy stte of growthF smportntlyD the mteril deposited during this stge n strongly impt mny properties of the resulting (lmD inluding its morphologyD surfe roughnessD rystl strutureD nd onformity with the sustrteD s well s it n determine the lowest hievle thikness for ontinuous (lmF por the synthesis of ultrEthin ny svs or tunnel rriers on snqes y evhD it is therefore impertive to understnd the di'erent proesses tht tke ple t the interfe during the (rst few yles of depositionF e employ n in situ synhrotron Ery pproh tht provides detiled struturl nd hemil insight during evh pong PHIHD ulug PHISD hendooven PHITF rereD we report detiled study on the struturl nd hemil evolution of ny lyers grown y evh on sn 0.53 q 0.47 es single rystl sustrtesD utilizing ustomEuilt retorD desried in ghpter PD tht permits the use of vriety of in situ synhrotron Ery tehniquesF his hs llowed us to monitor the inipient growth of ny ultrEthin (lms on tomilly )t sn 0.53 q 0.47 es nd determine the (lm struture yleEyEyle until stedy stte of growth ehvior is rehedF 4.2 Experimental Section 4.2.1 Substrate preparation he sn 0.53 q 0.47 es sustrtes @see ghpter ID setion IFIFPA were gitted in Rw rgl solution for S min to remove the ntive oxide un PHHVD rinsed in deionized wter for QH sD then dried with rgon efore immedite introdution into the evh retorF he smples were nneled t PHH • g for 30 min in the retor under onstnt )ow of IHH sm nitrogen to evporte es from the surfeF 4.2.2 ALD reactor and parameters of deposition ltrEthin lyers of ny were grown y evh in retor speilly designed for in situ Ery studies foihot PHITD desried in ghpter PF hiethylzin n@g 2 r 5 A 2 4.2. Experimental Section 77 or hin ws used s the n preursor @with the liquid mintined t 40 • gA nd room temperture r 2 y employed s the oxidntY ergon nd xitrogen were used to purge the retor nd gs linesF e investigted three di'erent sustrte temperturesX 100 • gD 120 • gD nd 140 • g in the evh window qo PHITF ih evh yle ws omprised of the following stepsX IF hin vpor enters the hmer nd rets with the smple surfeY PF the hmer is purged with x 2 D removing ny residul preursor nd retion produtsY QF r 2 y vpor is introdued into the hmerD reting with the surfeY RF the hmer is gin purged with x 2 to remove ny residul oxidnt nd retion produtsF rior to every introdution of preursor or oxidntD the pressure of the hmer ws reduedD nd the vlve seprting the hmer from the pump ws losedF he )ow of pure hin ws S sm for S sF he oxidnt @r 2 y vporA ws introdued either in gs mixture @moist irA or s pure gs @evported deionized wterAF he )ow of moist ir @respF wterA ws IHH sm for IH s @Q sm for RH sAF por the purging stepD we mintined x 2 )ow of IHHH sm for RS s while the hmer ws ontinully pumpedF 4.2.3 In situ synchrotron X-ray measurements he ustomEuilt evh retor foihot PHIT is equipped with polyether ether ketone @iiuA window for in situ synhrotron Ery mesurements nd ounterE rotting )nge to llow rottion of the smple ut not the retor odyF he retor ws mounted onto sixExis tower of hevyEduty di'rtometer @xewportA instlled t the ss emline of the yvisv synhrotron gitto PHIT @see setion IFQFI of ghpter IAF he emline fetures rQT pple P undultor soureD i@IIIA monohromtorD nd tEoted mirrors for hrmoni rejetionD providing photon )ux on the smple of ∼ Q × IH 12 phGs t IH keF Ery re)etivity @A nd Ery )uoresene @pA dt were reorded t IH ke @ove the n uEedge t WFTSW keA either during eh evh yle or fter the ompletion of severl evh yles @without ErysA while purging the retor with nitrogen )ow of IHH smF he Ery sorption spetrosopy mesurements were performed ross the n uE edge in )uoresene modeD using fourEelement silion drift detetor @hhA mounted QH • ove the surfe plneF he inidene ngle ws set to IFU • D well ove the ritil ngle for sn 0.53 q 0.47 es t IH ke @HFPS • AF es the smple surfe ws nerly horizontl nd the Ery polriztion ws liner nd horizontlD the eletri (eld ws in the plne of the smpleF reneD the Ery sorption nerEedge struture spetrosopy @exiA results re sensitive to the oritls oriented prllel to the surfe plne frouder IWWHF hile selfEsorption orretions re negligile due to the very low (lm thiknessD ll p nd exi dt hve een orreted for instrumentl nonlinerities gitto PHHRF 78 Chapter 4. Synchrotron in situ studies, part I (SIRIUS-SOLEIL)

Ex situ measurements

o study the growth mehnism of ny on the sn 0.53 q 0.47 es surfeD we performed etomi pore wirosopy @epwA on series of nyGsn 0.53 q 0.47 es smples grown t T = 120 • gD using fruker himension son etomi pore wirosope T M F ell evh prmeters were the sme s those given ove in setion RFPFPD exept the totl numer of evh yles whih vried from S to SHF rnsmission eletron mirosopy @iwA oservtions were rried out t PHH k with tiyv PHIH mirosope @with resolution of ∼ 0.19 nmAF grossEsetioned smples were prepred y oth mnul nd utomted polishingD the ltter using the wultirep T M system @ellied righ eh rodutsD snFAF he (nl polishing ws performed using feltEovered dis impregnted with sili solution until the pperne of the (rst extintion fringe mong those of equl thiknessF erEion milling ws then used to minimize the totl thiknessF 4.3 Results

XRF during growth

pigure RFIX @A n u α Ery )uoresene intensity @T substrate = 120 • gA vsF yle numerF he insets show the n )uoresene intensity @green urveA t the erly stgesD s ompred with intensity t the lter stges @ornge urveAF @A he experimentl n )uoresene intensity @light lue urveA nd (t @drk lue urveA for yles ISEQHF he inset shows the )uoresene intensity nd (t urve for yle PRF flk losed irles indite the n )uoresene intensity t the end of the hin pulseD nd red losed tringles indite the n )uoresene intensity t the end of eh evh yleF pigure RFI@A shows the evolution of n u α )uoresene intensity s funtion of the numer of evh yles for T substrate = 120 • CF he overll p urve is not liner ut exhiits n Eshpe @sigmoidlA trnsition etween two liner regionsF 4.3. Results

79

he regions orrespond to low growth rte @yles IEPSA nd the stedyD lyerEyE lyer growth ove yle ∼ SSF e loseEup of the region etween yles H nd IH is shown in n inset y the green urveF es eh evh yle egins with hin pulse lsting S sD there is jump in n )uoresene intensity t the strt of eh yleF por yles I to PUD the jump is followed y dey tht stems from the desorption of n @n tomsD nEontining moleulesD hin moleulesD nd other produts of the retionA from the sn 0.53 q 0.47 es surfeF he dey is sent t higher numer of ylesD nd )t )uoresene intensity is oserved fter the hin injetion @ornge urve in pigF RFI@AAF o investigte the n desorption ehviorD we (t the time dependene of the Ery )uoresene using liner omintion of n exponentil dey nd lineF he results re shown in pigF RFI@AD where the drk lue (t urve is plotted on top of the light lue experimentl urveF he di'erene etween the n )uoresene intensity t the end of the hin pulse for eh yle n @lk losed irles in pigF RFI@AA nd t the end of eh full evh yle @red losed tringlesA is displyed in the upper pnel of pigF RFP s funtion of numer of ylesF xote tht the noise oserved on the experimentl urve is likely not only from the numer of ounts ut lso from the reproduiility of eh evh yleF his involves the hemil retions tht tke ple on the surfeD the )ow of nitrogen etween evh pulsesD nd the pressure hnge inside the retor hmer during the four di'erent evh stepsF ell of these ftors impt the presene of hin moleules or n toms on the smple surfeF king into ount these possile vritionsD we (nd tht n desorption no longer tkes ple or is minimized fter ∼ 28 evh ylesF e rossEsetionl iw imge of the smple fter PS yles is shown in pigF RFQD it revels the presene of uniformD IFQEnmEthik morphous ny lyerF his suggests tht the end of n desorption is ssoited with omplete oting of the sn 0.53 q 0.47 es surfeF he trnsition etween regions s nd ss of pigF RFP mrks phenomenologil hnge due to the ft tht ny strts to grow on ny rther thn on snqesD whih leds to hnge from Ph to Qh growth ehviorF es lredy notedD the evolution of n u α )uoresene intensity in pigF RFI@A is not simple funtion of yle numerF e plot in the lower pnel of pigF RFP @(lled tringlesAD the mount of growth per yleD s mesured y p @qg@pAAF hese vlues orrespond to the di'erenes etween the (t vluesD shown in pigF RFID tken t the end of yle n nd (n -1) nd re plotted vs yle nF por omprisonD we lso plot the )uoresene growth per yle otined from the di'erene etween the (t vluesD shown in pigF RFID tken t the end of the hin pulse t yle n nd t the end of yle (n -1) @open irlesAF he urve represents the qg s it would hve een without the in desorptionF feyond the region where desorption is deteted @in region sAD the experimentl qg@pA inreses nd rehes mximum t yle QV efore deresingF his growth ehvior is known s type ss sustrteEinhiited growthD whih inludes islnd growthD oleseneD nd stedy stte growth xilsen PHHUD nd is disussed further in setions RFQFP nd RFRF 80 Chapter 4. Synchrotron in situ studies, part I (SIRIUS-SOLEIL) pigure RFPX pper pnelF hi'erene etween the n )uoresene intensity (t vluesD shown in pigF RFID tken t the end of the n pulse nd t the end of eh yleD s funtion of numer of yles @T substrate = 120 • CAF he (t urve is sigmoidl funtionF vower pnelF ringlesX pluoresene growth per yle @qgA otined from the di'erene etween the (t vluesD shown in pigF RFID tken t the end of yles n nd (n-1) vs yle nD vlues @T substrate = 120 • gAF ypen irlesX )uoresene growth per yle otined from the di'erene etween the (t vluesD shown in pigF RFID tken t the end of the hin pulse t yle n nd t the end of yle (n -1)F egion s orresponds to the detetion y p of desored moleules ontining nF e trnsition region is oserved when going from region s to region ssF 4.3.2 Atomic force microscopy e show in pigF RFR Ph epw imges of ny thin (lms grown on sn 0.53 q 0.47 es sustrte for di'erent numer of ylesF Qh imges re shown in pigF fFS @eppendix fAF he terre height vrition is shown y hnge of olor shde from drker @the minimum vlue is H nm E lkA to lighter @the mximum vlue is U nm E whiteAD with ll imges plotted ording to the sme height sleF e typil epw imge of the sustrte surfe fter the Rw rgl eth step is shown in pigF RFR@AF he presene of steps nd terres on the surfe of the sn 0.53 q 0.47 es sustrte re lerly visileF he height of eh step ws systemtilly mesured long series of prllel lineEsns ross the epw imgesF e typil sttistil distriution of step heights is shown in pigF fFT @eppendix fAF es the sn 1-x q x es lttie prmeter a n e determined y the egrd9s lwD it depends on the rtio etween the mounts of sn nd q tomsF sn the se of sn 0.53 q 0.47 esD the lulted lttie prmeter (a) t room temperture is 0.586 nmD whih is the sme s tht of snF eording to the experimentl distriution of step heights in pigF fFT @eppendix fAD the most likely vlue orresponds to step height of one unit ellD aF he other three possile vlues re 0.5aD 1.5a nd 2aF he root men squred @wA surfe roughness ws determined for eh individul terre nd verged out of series of w@epwA mesurements on severl terresF he w@epwA vlues re shown in pigure RFQX iw rossEsetionl imge of ny lyer on sn 0.53 q 0.47 es otined fter PS evh yles @T substrate = 120 • gAF pigure RFRX ost growth epw imges of ny (lms grown on sn 0.53 q 0.47 es for di'erent numer of ylesX H @AD S @AD IH @AD IS @dAD PH @eAD PS @fAD QH @gAD RH @hA nd SH @iAF e Qh rendering of the sme imges is shown in pigF fFS @eppendix fAF pigF RFSF ividentlyD fter S evh yles @pigF RFR@AAD fintD disontinuous deposit ppers on the sn 0.53 q 0.47 es terresD leding to slight inrese in w@epwA surfe roughnessD s n e seen in pigF RFSF es more mteril is depositedD the terre roughness ontinues to growD nd the presene of isolted pltelets eomes 82 Chapter 4. Synchrotron in situ studies, part I (SIRIUS-SOLEIL) more evident @pigF RFR@AAF e perolted ultrEthin (lm forms fter IS ylesD s shown in pigF RFR@dAF roles re lerly visile t this stge @drker spots on the terresAF iventullyD the holes (ll with more deposited mterilD nd oth the hole dimeter @pigF RFR@eAA nd terre roughness @pigF RFSA dereseF e more uniform terred surfe n e seen in pigF RFR@eA t yle PSF efter PS ylesD pigure RFSX w@epwA roughness of the sn 0.53 q 0.47 es terres s funtion of evh yle numerF he epwEdetermined vlues were lulted y verging difE ferent w@epwA roughnesses otined on severl terresF xote tht the w represents surfe height vritions with lterl sle of the order of PHESH nmF Qh islnd growth eginsX right spots on drk kground re visile in pigF RFR@fA nd RFR@gAF eording to the exi spetr @setion RFQFRAD these right spots my orrespond to ny islnds with shortErnge order struture similr to tht of wurtziteF pigure RFR@gA shows tht for yle QHD the verge islnd size hs inresedD lthough there is still some vrition in islnd shpe nd dimeterF et yle SH @pigF RFR@iAAD the surfe is griny with wellEde(ned right spotsD inditing the formtion of nnoprtilesF he w@epwA roughness ppers to level o' y yle SHD s seen in pigF RFSF es hs een pointed out in setion RFQFID ny growth on sn 0.53 q 0.47 es n e divided into two stgesX the (rst is hrterized y low nd nerly onstnt growth rte onomitnt with the detetion of n desorptionD nd the seond is hrterized y islnd growth without ny detetle n desorptionF e smooth trnsition ours etween the two stgesD s the (rst one is not (nished efore the seond one strtsF sn the sme wyD the epw imges show tht Ph lyer initilly forms on the tomilly )t sn 0.53 q 0.47 es terresF henD Qh ny islnd growth egins efore totl olesene of the initil lyerF he surfe roughness inreses s funtion of evh yle numerD with the grdul formtion of ny nnoprtilesF 4.3.3 Film mean thickness and growth rate he thikness of the ny lyers s funtion of the numer of yles ws investigted for three di'erent sustrte tempertures in the evh windowD T substrate aIHH • gD 4.3. Results

IPH

• gD nd IRH • gF ivery S evh yles up to yle SHD series of Ery mesureE ments @)uoresene nd re)etivityA were onduted in IHH sm of )owing x 2 F he Ery re)etivity urves re shown in the inset of pigF RFTF he dt orrespond to sustrte temperture of IPH • gF he thikness fringes result from the di'erent lyer densities in the diretion perpendiulr to the smple surfeD whih inlude the growing ny lyerD the PUHEnmEthik sn 0.53 q 0.47 esD nd IHEnmEthik sn u'er lyer on the sn rystlF pits to the urves @inset of pigF RFTA llow determinE pigure RFTX ny lyer thikness s funtion of the evh yle numer for suE strte temperture equl to IHH • gD IPH • g nd IRH • gD extrted from Ery reE )etivity urves mesured during growth every S yles in N 2 )owF snsetX experimentl @lue linesA nd (t @lk linesA urves s funtion of evh yle numer for sustrte tempertureD substrate = 120 • CF tion of the ny men thiknessF roweverD s the ny lyer is not ontinuous in the erly stges of growth @setion RFQFPA or its thikness is so smll @elow IEP nmA tht osilltions re rely detetedD the thikness ould not determined elow QH yles with suh dtF he dependene of the ny lyer men thikness µ on yle numer for di'erent sustrte tempertures is shown in pigF RFTF he trend of the n u α )uoresene s funtion of the numer of yles is similr to tht of µ s the )uoresene intensity nd the men thikness re oth proportionl to the numer of toms per unit volumeF rereD the experimentl thikness vlue of the ny lyer t yle SH @using oth nd the iw mesurementA ws used to lirte the )uoresene intensity urvesF he resultD whih now inludes dt for yles IEPSD is shown in pigF RFU@AF ith this informtionD the growth per yle @qgA n e found in strightforwrd wy y di'erentiting the thikness urve s funtion of yle numerF pigure RFU@A shows the vlues of the derivtive of the lirted )uoresene urvesF he height nd width of the qg@pA pek vry for the di'erent sustrte tempertures substrate F he highest nd the widest qg@pA pek is oserved for IPH • g sustrte temperture urveF sn dditionD the experimenE tl qg@pA urve strts to rise erlier for substrate = 120 • g @round PH ylesA ompred to the other sustrte temperturesF hespite the di'erenes etween the 84 Chapter 4. Synchrotron in situ studies, part I (SIRIUS-SOLEIL) pigure RFUX @A ny lyer @(lmA men thikness s funtion of yle numer for three di'erent sn 0.53 q 0.47 es sustrte temperturesY n u α )uoresene intensities were lirted with mesurementsF @A ixperimentl ny (lm men growth qg@pAF he Ery )uoresene @pA dt were reorded fter the ompletion of evh yles @whih took ple without ErysAF qg@pA urvesD ll three reh roughly the sme vlue t yle SHF 4.3.4 Fluorescence X-ray absorption near edge structure pigure RFV shows the exi spetr for di'erent yle numersF hey pper very similr in region sD regrdless of the prtiulr lyer thiknessF his suggests tht the n hemil stte nd lol environment do not hnge signi(ntly up to yle numer PHF prom the nlysis presented in previous work ghu PHITD we (nd tht the exi spetr revel disordered mteril with emryoni shortErnge orderX the y nerest neighors of n reside t the expeted distnes nd ngles for the wurtzite strutureD t lest within the smple plneF xo outEofEplne shortE rnge order is developed eyond the (rst shell in region sF huring the trnsition to region ssD new fetures pper on the exi spetr @eD fD gD hD nd i in pigF RFVAD inditing tht the n lol environment egins to strongly resemle tht of the wurtzite strutureF eording to the epw imges nd qg urvesD these yle numers lso orrespond to the onset of Qh islnd growthD s desried in setion RFQFQF roweverD iw imges nd di'rtion sns otined t the end of region sD like the one shown in pigF RFQD show no evidene for longErngeD rystlline orderF his ws oserved lso t the erly stges of ny evh on morphousEiy 2 t growth tempertures similr to those here pong PHIHF 4.4 Island growth modeling he experimentl qg@pA urves were (t in region ss @pigF RFPAD ording to the growth model of hemispheroidl islnds desried in ghpter QF e represent pigure RFVX ixperimentl n uEedge exi spetr for yles 1 -35 of the evh growth of ny on sn 0.53 q 0.47 es sustrteF ell spetr hve een normlized to the sme jump vlue t the edge nd shifted long the yExis for lrityF he spetr orresponding to yle I nd P re nerly identil nd were verged to improve the signlEtoEnoise rtioF he yle numer is indited to the right of eh spetrumF imryoni urtzite struture @green solid linesAD rising of the urtzite struture @ornge solid linesAF sustrte inhiited growth of type P in region ss @possily used y hnge of surfe roughnessA s n equivlent growth of hemispheroidl islndsF sn tht regionD we ssume tht ∆r nd ∆h @inrementl inrese of islnd se rdius nd islnd heightA re onstnt nd equl @i.e.D tht the growth is isotropi nd the qg= ∆r = ∆hAF e de(ne (h/r) 0.05 s the initil islnd spet rtio t the onset of islnd growth tht orresponds to qg lose to HFHS nmFy -1 F ynly ∆r = ∆h nd (h/r) 0.05 were llowed to vryF egion sD exept in the trnsition regionD ws exluded from our model sine the inrementl inreseD ∆r = ∆hD is lower in region s due to n desorptionD resulting in di'erent growth ehviorF hetermining the vlue of ∆r = ∆h should e strightforwrdD s the experimentl qg@pA urve in pigF RFU pprohes it for lrge numer of ylesF roweverD our dtset is limited nd does not rrive t onstnt vlue fter SH ylesF fut it ws possile to otin the experimentl vlue of ∆r = ∆h y (tting the qg@pA urve t the left side of the qg@pA mximum @hse sA with eqution QFQI @see setion QFR of ghpter QAD where n c is known experimentl vlueF sing eqution QFPID we lulte ∆rF henD the ∆r nd n c vlues were used to simulte the entire qg urve with the hemispheril islnd modelD s desried in ghpter QF pigure RFW shows the experimentl qg@pA dt t di'erent sustrte temE perturesD T substrate = 100, 120, 140 • g @see pigF RFUAD nd the modeled qg urves for region ssF he inset of pigF RFW shows the experimentl qg@pA dt t T substrate = 120 • gD whih orresponds to the qg urve in pigF RFP efore lirE tionD nd the modeled qg urvesF he results of modeling indite tht di'erent pigure RFWX ixperimentl mesurements of growth per yle @qgs@pAA @(lled symolsAD nd the simultion urves from islnd growth model @solid linesAD s funE tion of yle numer nd for di'erent sustrte tempertures @IHHD IPH nd IRH • gAF he mesurements were performed in etween growth ylesF he simultion pE rmeters re given in the textF he inset displys the experimentl mesurement of the qg performed during growth t T substrate = 120 • g @open irleAF he experiE mentl qg ws shown in pigF RFP efore lirtionF hown re simulted qg urves for di'erent islnd spet rtiosD @hGrA 0.05 D t the onset of islnd growth tht orresponds to qg lose to HFHS nmFy -1 Y @hGrA 0.05 aI @lue solid lineAD IFS @violet dottedEdshed lineA nd HFS @rown dshed lineAF he dotted red line is the sum of the lue solid line nd the lk dottedEdshed line whih represents the qg urve in region sF he qg simultion urves hve een shifted long the horizontl xis to region ss y the yle numer of inution n inc F slopes nd pek heights of the qg urve during hse sD i.e.D efore oleseneD n e otined with devitions in the ∆r = ∆h vlues ndGor preEolesene roughE ness @with lrger roughness implying more surfe ville for growthAF hi'erent preEolesene roughnesses n e hieved y vrying the initil islnd spet rtio (h/r) t the onset of islnd growth in hse s @with the experimentl qg vlue eing lose to HFHS nmFy -1 in the present studyAF por instneD the inset of pigF RFW shows the experimentl qg urve t T substrate = 120 • g @open irleA nd lulted urves otined with di'erent initil islnd spet rtiosX @hGrA 0.05 equl to one @lue solid lineAD greter thn one @violet dottedEdshed lineAD nd less thn one @rown dshed lineAF rereD the qg vlue ws set to HFIW nmFy -1 F he e'et of @hGrA 0.05 on pek height is lerly visileF he est (t vlues of the qg nd initil islnd spet rtios for the three qg urves shown in pigF RFWD s well s the le RFIX fest (t vlues of qg@= ∆r = ∆hA nd @hGrA 0.05 otined for the modeling of the experimentl qg@pA urves shown in pigF RFWF @ • gA is the sustrte tempertureD qg is the growth per yleD @hGrA 0.05 is the islnds initil spet rtio for qgaHFHS nmFy -1 F w 0.05 nd w max re the lulted root men squred roughness vlues t qgaHFHS nmFy -1 nd t the mximum of the qg urveD respetivelyD N d = 1/b 2 is the islnds densityF @ • gA IPH IRH IHH qg @nm.cy -1 A HFPI HFPI HFPI @hGrA 0.05 IFQP HFVI HFRU w 0.05 @nmA HFQP HFPT HFIV w max @nmA IFRQ IFIT HFWP N d @IH -2 nm -2 A IFVU IFVU IFVU lulted root men squred roughnesses nd islnd densitiesD re given in le RFIF he qg vlues re the sme for the three tempertures nd equl to HFPI nmFy -1 D vlue tht ompres well to the highest vlues found in the literture ynell PHIR nd is lose to tht expeted for ny wurtziteF sdellyD tomi lyer deposition would give qg of HFPT nmFy -1 Y experimentllyD howeverD it is unlikely to reh suh vlue qo PHITF he di'erent pek heights of the qg urves is quite well reprodued with di'erent initil islnd spet rtios tht re less thn ID less thn ut lose to ID nd greter thn one for T substrate = 100, 140, 120 • gD respetivelyF hese simultions suggest tht di'erent preEolesene roughnesses during hse sD stemming from the slightly di'erent growth onditionsD ould result in vritions of the qg pek heightD ut the stedyEstte qg vlue @t yles > 55A remins the smeF he inset of pigF RFW shows representtion of the qg urve in region s y sum of two funtionsX slightly inresing stright line @until out yle PHA nd sigmoidl funtion tht goes to H ove yle QH @lk dottedEdshed lineAF he ltter is very similr to the one shown in pigF RFP @upper pnelAD i.e.D it hs the sme width nd is entered on the sme yle vlueF snterestinglyD one n see tht the modeled qg urve @red dotted lineA tht is the sum of the qg urves in region s @lk dottedEdshed lineA nd ss @lue solid lineA perfetly (t the qg experimentl vlues in the trnsition regionF ueeping in mind tht the sigmoidl urve in pigF RFP represents n desorptionD this result further indites tht the trnsition region from the region s to region ss is orrelted with deresing n desorptionF 4.5 Discussion e hve demonstrted ove tht ny evh on sn 0.53 q 0.47 es is hrterized y n initil trnsient regime omprised of Ph growth nd Qh islndingD followed y stedyEstte growth regime with growth rte of 0.21 nmFy -1 F sn the se of oxide evh with hydrogen trnsfer retions nd wter used s n 88 Chapter 4. Synchrotron in situ studies, part I (SIRIUS-SOLEIL) oxidntD one evh yle omines two selfEterminting hlf retions rwng PHIQD uurunen PHHRF he (rst hlf retion is the retion of metl preursorD M L n D with n yrEterminted surfeX

M -OH * + M L n -→ M -O -M L * n-1 + HL @RFIA
where M is the metl nd L is the ligndF huring the seond hlf retionD wter reples the dsored lignd with n yrEgroupX

M L * + H 2 O -→ M -OH * + HL. @RFPA
he proility of preursor dsorption nd its hemil retion diretly 'et the initil growth ehviorF st is known tht there re severl possile initil growth ehviors uurunen PHHRX stedy liner growthD sustrteEenhned growthD nd sustrteEinhiited growthF sf the numer of retive sites on the re sustrte is higher or lower thn on the evhEgrown mterilD either sustrteEenhned growth or sustrteEinhiited growthD respetivelyD n ourF sf the sustrte surfe is not highly retiveD growth ours minly on the more retive resF his leds to surfe inhomoE geneity nd is the origin of sustrteEinhiited growth ehvior fji PHIPF es the islnd size inreses nd growth enters the olesene stgeD Ph lyer is formedF sf the evhEgrown mteril surfe is fully overed y hemilly retive sitesD stedy liner growth ehvior n eginF e trnsient growth regime hs lredy een reported for vrious mterils grown y evhF ilm et al. ilm PHHI used euger eletron spetrosopy to exmine the initil stges of tungsten growth on iy 2 sustrteF hey oserved liner Ph growth for (rst few evh ylesD ut the growth rte ws lower thn for stedyEstte growthF he uthors dmit n equl proility of Ph nd Qh growth ehvior during the initil stgeF uim et al. uim PHIH lso showed tht for u (lm depoE sition on ix nd iy 2 D the trnsient region ws presentF qrowth ws inhiited for (rst severl evh yles due to the wek intertion etween the u preursor nd the ovlent onds in ix nd iy 2 F purthermoreD for the sme mteril deposited on di'erent sustrtesD the inution time @or yle numer efore the Qh growth eginsA n vry or e sent entirelyF vim et al. vim PHHH showedD using simple nlytil kineti modelD tht t the eginning of growth trnsient regime exists until the deposited mteril fully overs the sustrte surfeY only then n stedy liner growth tke pleF husD the inution time ould orrespond to the time neessry to over the totl sustrte surfeF tt et al. tt PHHP investigted iy 2 surfe overge on iy 2 sustrtes s funtion of the numer of deposition ylesF hey demonstrted slowD liner inrese of surfe overge in the (rst stge of growth due to nonEretive surfeF henD sine the proility of dsorpE tion vries on mixed surfeD this led to Qh islnd growthF heposition eventully entered stedy liner growth regimeF qreen et al. qreen PHHP oserved similr growth ehvior for rfy 2 on i sustrtesF he i sustrte surfe ws oxidized y di'erent wysD nd the uthors showed tht thin oxide lyer @less thn I nmA hnges the properties of the smple surfeD impting the initil growth stgeF hey lso found tht the proility of strting hemil retion is higher when the iy x surfe is terminted with yrEgroupsF sn the present studyD we hve evidened trnsient regime tht we divide into two steps @regions s nd ssD s indited in pigF RFPAF egion s orresponds to regime in whih nEontining moleules desor from the surfeD s deteted y pF rereD the growth rte is very low @< 0.05 nmGyleA nd nerly onstntD s long s the n desorption mgnitude is out the smeF e trnsition stge then tkes pleD nd the qg strts to inrese s the mount desored dereses @pigF RFPAF egion ss is hrterized y the sene of preursor desorption nd rpid hnge in growth rteD s desried in setions RFQFP nd RFRF xote tht only hemilly dsored hin preursor or nEontining moleules re deteted in our experimentsD sine physilly dsored moleules n e esily removed during the x 2 purging step uurunen PHHSD im PHHVF es ws shown in pigF RFPD there is no evidene of n desorption fter PV evh ylesF sn the region sD the low nd nerly onstnt growth rte @qgA is ssoited with the inertness of the sustrte surfe nd nerly onstnt stiking oe0ientF his is likely to e ssoited with low density of tive sites @eFgFD yr groupsA uurunen PHHSD pily PHIHD qreen PHHP whih hmpers preursor @hinA nd retnt @r 2 yA hemisorptionF huring the oxidnt pulseD wter rets with the smE ple surfe nd leves tive sites for retion with hinY these hemil retions re given y equtions RFI nd RFPF sndeedD we show in pigF fFU @eppendix fA tht inresing the wter )ow shortens the dely in ny nuletionD most likely due to inresed tive site density on the sn 0.53 q 0.47 es surfeF snterestinglyD s oserved in pigF RFWD the mount of n deposited fter the (rst yle is out three times higher thn the following few ylesD nd there is lmost no desorptionF his indites tht surfe funtionliztion hnges fter the (rst yle wheres it does not for the susequent yles @until ny no longer desorsAF e lose inspetion of the epw imges strongly suggests tht the fding of the desorption stge is orE relted with the losure of Ph lyerD whih is onomitnt with the onset of Qh ny islnds @orresponding to the trnsition stge in pigF RFPAF pigure RFP shows tht in region sD the n desorption mount stys onstnt for eh yle despite the ft tht the sn 0.53 q 0.47 es nd ny surfe frtions vry during growthF his suggests tht the n nd oxygen toms inorporte preferentilly t the edge of the plteletsF ell of these p nd epw oservtions indite tht growth in region s onE sists of period of inution with low growth rteD during whih the sustrte surfe trnsforms its funtionl groups nd results in the frition of Ph lyer tt PHHPF e PhElike mehnism of growth distinguishes this phseF egion ss is hrterized y n sene of preursor desorption nd ny islnd growthF es shown in pigF RFPD eyond yle PSD the ny islnds strt to grow on the surfe of the Ph ny lyerF he epw imges @pigF RFR@fEiAA provide evidene for high density of islnds with rther lrge size distriutionD suh tht it is di0ult to distinguish wellEseprted islndsF roweverD it is ler tht the verge islnd 90 Chapter 4. Synchrotron in situ studies, part I (SIRIUS-SOLEIL) dimeter inreses s funtion of evh yle numerF purthermoreD islnd growth is ompnied y hnge in the surfe roughness @pigF RFSAF eordinglyD the men thikness urves @pigF RFU@AA show the typil Eshpe in region ss ssoited with Qh islnd growth nd olesene xilsen PHHUD uurunen PHHRF he formtion of Ph ny lyer on the sn 0.53 q 0.47 es surfe followed y Qh ny islnd growth is skethed in pigF RFIHF pirstD the sn 0.53 q 0.47 es surfe @pigF RFIH@AA strts to e overed with pltelets @pigF RFIH@A nd RFIH@AAD nd the smple surfe roughness inresesF ight efore ompletion of the Ph ny lyerD holes re visile t the surfe @pigF RFIH@dAAD whih then shrink @pigF RFIH@eAAF he iw imge revels tht the Ph lyer is morphous @pigF RFQAF he exi spetr @pigF RFVA on(rm tht the tomi struture of the Ph nEoxide lyer is disordered ut hs n emryoni wurtzite strutureF ny islnd growth strts on top of the Ph ny lyer @pigF RFIH@fAAD nd the growth rte @qgA rehes onstnt vlue fter the trnsient regimeD s seen during sustrteEinhiited growthF he simple growth pigure RFIHX hepition of the di'erent growth stgesX @A re sn 0.53 q 0.47 es surfeD @A initil ny islnd nuletionD @A islnd density inreseD @dA 4hole4 formtionD @dA Ph ny lyer formtion @wurtzite strutureAD nd @fA the islnd growth phseF model proposed in ghpter Q llows us to nlyze the qg urvesF he simultions suggest tht di'erent preEolesene roughnesses during hse s ould result in vritions of the qg pek heightD while the stedyEstte qg vlue @t yles > 55A remins the smeD s is the se for the three qg@pA urves reported in pigF RFU@AF he lowest roughness in the trnsient regimeD notly t the mximum of qg urvesD is hieved for the lowest tempertureF he qg vlues re out the sme nd equl to HFPI nmFy -1 for the three sustrte tempertures @IHH • gD IPH • g nd IRH • gAF his is in greement with the ft tht these three temperture vlues re ll within the evh temperture window @see setion IFPFP in ghpter IAF

Conclusion

e hve performed the (rst detiled study on the evolution of the growth proess during the initil stges of ny growth on sn 0.53 q 0.47 es y evhF st ws demonE 4.6. Conclusion 91 strted tht growth psses through trnsient stge efore the onset of stedyEstte growthF he trnsient stge is omprised of two regimes seprted y trnsition stgeF sing in situ synhrotron Ery )uoreseneD re)etivityD nd sorption spetrosopyD we hve demonstrted tht the (rst regime of growth @up to PV yE lesD region sA is fr from idel evh growthF huring this regimeD we (nd tht the sustrteEinhiited ny growth mode tkes ple on snqes terresF st results in slow growth rte @< HFHS nmFy -1 A with the desorption of moleules ontining nF his leds eventully to the formtion of ∼IEnmEthik Ph morphous ny lyer @t out yle PSAF fy the end of the (rst regime @region sAD trnsition oE urs in whih the qg strts to inrese when the mount of desorption deresesD nd growth enters into seond regime @region ssAF he phenomenologil model we developed @see ghpter QA to desrie the hnge of qg ehvior suggests Qh islnd formtion in region ssD with n islnd spet rtioD i.e. initil surfe roughE nessD tht depends on the growth onditionF he trnsient regime @regions s nd ssA ends with islnd oleseneF he growth is (nlly hrterized y stedy growth rte of HFPI nmFy -1 D s expeted for lyerEyElyer ny evhF his shows tht idel evh ehvior is not lwys hievleD espeilly t the initil stges of heterogeneous growthF yur work demonstrtes the unique power of in situ synhrotron methods for eluidting the tomisti proesses tking ple during the initil stges of evhF e (nd tht the omplementry suite of tools used here is key to optimizing the growth proess nd mteril qulityF purthermoreD the suessful growth of IEnmE thik Ph ny lyer is highly enourging for the future development of ny svs nd sssE surfe pssivtionF Chapter 5

Synchrotron in situ studies, part II (ID3-ESRF)

In this chapter, we show the eect of the water precursor ow and the substrate temperature values during ZnO ALD on the growth of the ZnO both in the transient regime and in the steady growth regime. This experiment was carried out on an ID3 synchrotron beamline (ESRF, Grenoble (France)), using the MOON reactor, described in Chapter 2, to monitor ZnO growth InGaAs in situ. For ZnO ALD we used diethylzinc (DEZn) as a metal precursor and H 2 O as an oxidant.

In the rst part of the chapter, we show how increasing the water precursor ow value aects the initial stages of ZnO growth on InGaAs. During ZnO growth, in addition to other measurements, we monitored the thickness of the ZnO layer, recording the change in the intensity of the reected X-ray beam from the substrate as a function of the cycle number. We show that this intensity oscillates as a function of the thickness. Then, we show that the lm thickness and the growth per cycle (GPC) demonstrate a low, almost zero, growth rate for the rst cycles, then substrate inhibited of type 2 growth mode begins, and nally higher cycle number steady state of growth begins.

We used our hemispheroidal-island model described in Chapter 3 for the analysis of GPC curves. We demonstrate that the water precursor ow changes the number of ALD cycles prior to substrate inhibited growth of type 2, and it changes GPC value in the steady growth state.

We have measured reciprocal space maps every few cycles during the growth of three samples grown at a substrate temperature in the ALD window (see Chapter 1). We show that the relative intensity of the ZnO diraction peaks onset depends on the ZnO thickness and growth temperatures. We also show that for a higher temperature (outside the ALD window), zinc oxide lm texture is observed at 100 cycles (corresponding to a lm thickness equal to about 14 nm).

Introduction

e rried out n in situ mesurements during ny evh on sn 0.53 q 0.47 es to study initil stges of growth y Ery tehniques t the shQ emline of ip @see setion IFQFPAF he min di'erene from the experiment desried in ghpter R @irius emline experimentA is tht during the evh proess we used deionized wter s n oxidnt from wter evportorD nd we foused on Ery sttering during evhD rther thn Ery sorption @epAF he sn 0.53 q 0.47 es sustrtes were hemilly treted efore loding into the retor hmerD s desried in the setion IFIFPFRF he sn 0.53 q 0.47 es sustrtes were gitted in Rw rgl solution for S min to remove the ntive oxide un PHHVD rinsed in deionized wter for QH sD nd then dried with rgon efore immedite introdution into the evh retorF he smples were then nneled t PHH • g for 30 min in the retor under onstnt )ow of IHH sm nitrogen to evporte es from the surfeF henD the sustrte ws heted up to the sustrte @ sub A tempertureF huring the experimentD for one set of smplesD we vried the wter )ow during evh oxidnt pulse to determine its in)uene on the initil stges of ny evh on sn 0.53 q 0.47 esF por nother set of smplesD we vried the sustrte temperture nd mesured di'rtion mps to monitor the ny rystlliztion t the initil stges of the evh growth s funtion of sustrte tempertureF por these smplesD Ery )uoresene @pA signl ws deteted during growthX the energy of the Ery em ws IH keF he n u α @VFT keA nd u β @WFSU keA )uoresene lines were deteted using )uoresene detetor @see setion PFPAF e lso mesured the intensity osilltions of the speulrly re)eted Ery em from the smple surfe t smll inident ngle @see setion SFPFIA nd for IH ke em energyF por the smples for whih the temperture of the sustrte ws vriedD we mesured 4onEtheE)y inEplne reiprol spe mpsD lled herefter zpEsns @see efF oool PHISA etween evh yles t n Ery em energy of PH keF et the end of the ny growth @fter IHH evh ylesAD we mesured Ery re)etivity @A urves t PH ke to determine the thikness nd roughness of the deposited ny lyersF por grown smplesD we studied the surfe topogrphy @roughnessD grin sizeA y etomi pore wirosopy @epwAF e used the tpping mode of fruker himenE sion son etomi pore wirosope T M F e lso heked the homogeneity of the n ontent in the grown smples y mesuring the Ery )uoresene signl indued y eletrons in nning iletron wirosope @iwAF inergyEdispersive Ery spetrosopy @ihA spetr were mesured on pield imission qun invironmentl nning iletron wirosope @piq iiwA unt T M PSHF o mesure )uoresE eneD n inergyEhispersive Ery @ihA detetor ws used @the eletron em energy ws Q keAF hese in situ studies llow to give insight on the struture evolution nd growth mode t the erly steps of the evh growth of ny lyers on sn 0.53 q 0.47 es nd to determine the in)uene of wter )ow nd sustrte temperture on the initil stges of the growthF 5.2 Oxidant ow variation e vried the )ow of wter for set of smplesD nd mesured the hnge of intensiE ties of the osilltions of the speulrly Ery em re)eted from the smple surfe during growthF sn the following setionD we give rief theoretil desription of how to nlyze the re)eted em intensity osilltionsF

Analysis of the reected beam intensity oscillations

huring the growth of nyD the Ery em impinges onto the surfe of the smple t n inident ngle α i F st is known thtD with hnge in the ny lyer thiknessD the intensity of the speulrly re)eted Ery em osilltes @inreses nd deE resesA elsExielsen PHIIF hese osilltions pper due to the interferene of the Ery em re)eted from the ny lyer surfe nd the Ery em trnsmitted through the ny lyer nd re)eted from the sustrte surfe @see pigure SFI@AAF por the se when the opti pth di'erene is multiple of the wve period @two wves re in phseAD n interferene mximum is oservedF hen the opti pth di'erene is multiple of the period of the wve shifted y hlf the period @wves re in out of phseAD then n interferene minimum is oservedF e mesured the intensity of the re)eted Ery em t n exit ngle α f @α i = α f AF he (gure SFI@A shows shemti representtion of the geometry of re)etion nd refrtion of the Ery em in ny lyer of thikness ΩF he Ery em impinges onto the surfe of the sl @or ny lyerAF he em n e either re)eted with n ngle α f or refrted in the lyer with n ngle A i egostini PHIIX

A i,f = 1 √ 2 (α 2 i,f -α 2 c ) 2 + 4β 2 + α 2 i,f -α 2 c 1/2 , @SFIA
where δ nd β re the rel nd imginry prts of the ny refrtive index n @n = 1 -δ + iβAD α c is the ritil ngle @α c = √ 2δD ngle of inidene elow whih totl re)etion ours E wvelength dependentAD α i nd α f re inidene nd re)etion ngles to the smple surfeF pigure SFI shows the wve vetors of the inident wve @ k I nd k I AD the trnsmitted wve in nother mteril @ k T nd k T A nd the re)eted wve @ k R nd k R AD q = k R -k I is wvevetor trnsferF he wve pigure SFIX @A hemti representtion of the geometry of re)etion nd refrtion of the Ery em in ny lyer of thikness ΩF @A Ω 0 /2 s funtion of the inident ngle α i for the speulr re)eted Ery em @α i = α f AF gurves re plotted for di'erent mterils of the slX lue dotted urve for snqesY nd yellowD ornge nd red solid urves re plotted for ny lyer with di'erent densities @100%D 80%D nd 60% of wurtzite ny densityAY green dshed urve is plotted for the se when

A i = α i F vetors k I D k T D nd k R re
written for the vuumD the wve vetors k I D k T D nd k R re written for the mteril with the refrtive index nF por wve re)eted y the surfe of the ny lyer nd the wve trnsmitted through the ny lyer nd re)eted y the surfe of the sustrte @the refrtion ngle is A i Y A i = A f AD nd leving the lyer t ngle α f @α i = α f AD the onditions for oserving the onstrutive nd destrutive interferene n e written sX q z Ω = m; m = 0, 1, 2, ...

q z Ω = (m + 1/2); m = 0, 1, 2, ... @SFPA where | q z | = | k Iz | + | k Rz | is
2n • ΩsinA i = λm; m = 0, 1, 2, ... @SFQA nd 2n • ΩsinA i = λ(m + 1/2); m = 0, 1, 2, ... @SFRA
espetivelyD where λ is the Ery wvelengthF prom expression SFQ @eqF SFRAD when one interferene mximum @minimumA is oservedD the ny lyer thikness should inrese y Ω 0 = λ/(2n • sinA i ) to oserve the next interferene mximum @minimumAF henD n inrese of hlf of Ω 0 in the thikness is needed to oserve the next interferene minimum fter mximum @or interferene mximum fter minimumAX

Ω 0 2 = λ 4nsinA i , @SFSA
sing the equtions SFI nd SFSD we plotted the dependene of the hlfEperiod of the thikness inrese needed to oserve onstrutive interfereneD s funtion of the inident ngle α i for the se of speulrly re)eted Ery em @α i = α f AF pigure SFI@A shows n exmple of suh dependeniesD for di'erent thin lyer mE terilsF he mteril prmeters nd n exmple of lulted Ω 0 /2 nd refrtive ngle A i for n inident ngle α i = 0.5 • re listed in the tle SFIF le SFIX el @δA nd imginry @βA prts of the refrtive index n @n = 1 -δ + iβADritil ngle α c for di'erent mterils nd densitiesD Ω 0 /2 nd refrtive ngle A i lulted for n inident ngle α i = 0.5 • F he Ery em energy used for lultions is IH ke @λaHFIPR nmAF vyer wteril β •10 -7 δ •10

-5 α c = √ 2δ @ • A A i @ • A Ω 0 /2 @
r slab (Ω) = q c 2q 2 (1 -e iqΩ ), @SFTA
where q c is the wvevetor t the ritil ngle nd Ω the sl thiknessF xote tht expression SFT is written for the ske of simpliity nd pedgogyD it is vlid with the ssumption tht there is no refrtion e'etD i.e. the re)etivity @intensityA t the irEny interfe is smllD nd the re)etivities @intensityA t the irEny nd nyEsnqes interfes re equlAF huring n experimentD re)eted em intensity is proportionl to the squre of the re)etivity mplitudeF henD we n write n eqution for the squre of re)etivity mplitude modulusD tken into ount the roughness of the interfes y multiplying the re)eted intensity y the term e -σ 2 q 2 z @see efF elsExielsen PHIIAD where σ is the root men squred roughness @unorrelted surfe heightAX R(Ω) ∼ 1 8 q c q 4

(1 + cos(qΩ)) e -q 2 σ 2 , @SFUA prom iqF SFUD we n onlude tht for (xed inident ngle α i @the trnsfer vetor q is (xedAD the inresing of the sl thiknessD ΩD leds the re)eted intensity to osillte like osine funtionF elsoD if the roughness σ inreses with thikness ΩD the osilltion mplitude deys exponentillyF 98 Chapter 5. Synchrotron in situ studies, part II (ID3-ESRF) 5.2.2 Monitoring ALD in situ during the growth e investigted how ny hnges for di'erent vlues of wter )ow pulse @see seE tion PFQFIAF e hose three di'erent vlues of wter )ow for three smplesX HFT sm @4HFT!sm4 smpleAD PFT sm @4PFT!sm4 smpleAD nd T sm @4TFH!sm4 smpleAAY nd the temperture of snqes sustrte ws set to IPH • gF huring evh proess we used n@g 2 r 5 A 2 or diethylzin @hinA s metl preE ursorD wter @r 2 yA s n oxidntD nd nitrogen @x 2 A s purging gsF por eh evh yleD the )ows of hin ws S smD nd pulse durtion ws 5sF por di'erent wter )owD wter pulse durtion ws lwys 40sF he x 2 )ow @IHHH smA ws injeted etween hin nd r 2 y pulses during 45s through retor hmer to the pump @retor hmer vlve ws openAF Ery mesurements were rried out during evhX during ll hemil retions @hin nd r 2 y pulsesAD the Ery em irrdiE ted the surfe of the sustrteF huring evh we mesured the integrted intensity of the n u α )uoresene pek nd the intensity of the re)eted em for hosen inident ngle α i D up to IHH evh ylesF efter the growthD Ery in plne reiprol spe mps were mesured y performing zpEsnsF pigures SFP@EA show the dependene of n u α )uoresene s funtion of yle numer n for three smples @wter )ows were HFT smD PFT smD nd T smD respetivelyAD mesured in situ during evhF sn the insets of eh (gureD it is shown tht t the eginning of eh evh yleD during the pulse of hinD there is n )uoresene jumpD s lredy disussed in the setion RFQFIF st n e noted tht the noise on the n )uoresene urves inreses with the inrese of the )uoresene intensityF e ssoite this with d settings of the )uoresene detetorF pigures SFP@dEfA show the hnge of intensity of the speulrly re)eted Ery em for the three smples s funtion of time @or yle numerAF ysilltions re oservedF unowing the vlue of the inident nd re)eted ngles of the Ery emD we n lulte the thikness hlfEperiod Ω 0 /2 of the ny lyerD expressed in nmD using eqution SFSD s desried in the setion SFPFIF por thikness lultionsD it ws ssumed tht the ny density of zin oxide is onstnt whtever the yle numerF o determine Ω 0 /2 for given inident ngle α i D we used the IHH% density urve shown in (gF SFI@AF henD we link to eh minimum nd mximum of the osilltions vlue Ω of the ny lyer thiknessF he thikness vlues re plotted on upper ΩExis in pigF SFP@dEfAF unowing the ny thikness for some of the yle numersD we n lirte the )uoresene urves @pigsF SFP@EAA nd plot the thikness urves s funtion of yle numerD sine the n p signl is proportionl to the ny thikness when ssuming tht the ny lyer density is onstntF por doing thtD we used the urves @osilltionsA shown in pigF SFP@dEfA nd retrieved the vlues of yle numer nd thiknessD for eh minimum or mximumF hese ouples of vlues re represented s red strs on (gures SFQ@EAF henD using one of these points @on pigF SFQ@EAD points whih we used for lirtion re irledAD we lirted the p urves s thikness urves of the ny lyer versus the numer of ylesF pigures SFQ@EA show the equivlent ny thikness determined y p @hikE pigure SFPX he dependene of n u α normlized )uoresene s funtion of yle numer n for three smples with di'erent wter )ow during oxidnt pulseX @A HFT smD @A PFT smD nd @A T smY sntensity of the speulr re)eted Ery emX @dA HFT smD @eA PFT smD nd @fA T smF he inident ngle α i ws HFSIS • for 4HFT!sm4 smple @A nd @dAD HFTIS • for 4PFT!sm4 smple @A nd @eAD HFTTS • for 4TFH!sm4 smple @A nd @fAF ny lyer thikness whih orresponds to the mximum nd minimum of the osilltions were lulted y iqF SFSF ness@pAA s funtion of the yle numer n for three smplesD with di'erent r 2 y )ows during the pulse of the oxidntF egrding the p dt redutionD we verged the signl intensity vlues mesured during one yleF husD in (gures SFQ@EAD one point orresponds to one yle numerF st n e seen tht t low yle numerD the ny thikness inreses slowlyF henD the hikness@pA urve inreses nonElinerlyF he inrese of thikness ours erlier for higher r 2 y )owF pinllyD ll the thikness urves reh liner regime @stedy growthAF sn the (gE ures SFQ@A nd SFQ@AD one n oserve tht the red strs pointsD retrieved from the intensity osilltions of the speulr re)eted Ery emD firly mthes the orreE sponding vlues of the hikness@pA urve in the stedy stge of growth regionF sn the trnsient region @efore stedy growthAD the thikness vlues re higher thn the hikness@pA vlues for the sme yle numerF his my e due to the ft tht the ny lyer density is lower @thikness to oserve interferene is smllerA in the trnsient region thn in stedy growth regionF purther investigtion must e rried out to lrify tht disrepnyF por more detiled nlysis of the hikness@pA urvesD we onsider the hnge of thikness per one evh yle or growth per yle @qgAF pigures SFQ@dE pigure SFQX @EAX ny equivlent thikness @hikness@pAA s funtion of the yle numer n for three smplesD with di'erent vlues of r 2 y )ow during the pulse of the oxidnt @@A HFT smD @A PFT smD nd @A T smA nd est (ts in liner region orresponding to stedy growth @red solid linesAF he red strs orrespond to thiknesses extrted from re)eted em intensity osilltion @see textAF @dEfAX glulted qg@pA urves for the three smples @r 2 y )ows during evh were @A HFT smD @dA PFT smD nd @fA T smA nd their qg urve simultions using model of hemispheril islnds @red solid linesA nd model of hemispheroidl islnds @green solid lineAF fA show lulted qg@pA urves for the three smples otined using the hikness@pA urves @pigsF SFQ@EAAF es n e seen in the qg urvesD t the eginning of growthD the qg lmost do not hnge nd show vlues lose to zeroF he growth of the mteril on the surfe is very slowF henD the qg urves strt to rise s funtion of yle numerF he yle numer t whih the qg strts to inrese is smller for smples for whih higher oxidnt )ow ws used during the evh proessF pinllyD qg urves reh mximum nd eome onstntF his qg growth ehvior orresponds to sustrte inhiited growth type ss @see ghpter QA uurunen PHHRF o extrt some growth prmeters from experimentl qgD we hve simulted qg funtion y pplying our geometri growth model for hemispheroidl islndsD presented in hpter QF e represent the growth of islnds of hemispheril shpe loted in squre grid with period bF he inrement of the hemispheroidl islnd height per yle @∆hA is the slope of the thikness funtion in the evh stedy regimeD euse simulted qg tends to this vlueF e (tted the liner region of thikness urves otined for the three smplesX 4HFT!sm4D 4PFT!sm4D nd 4TFH!sm4F pits were performed in the region etween WH nd IHH yles for 4HFT!sm4 smpleD etween UH nd IHH yles for 4PFT!sm4 smpleD nd etween UH nd VH yles for 4TFH!sm4 smple @red solid lines in pigsF SFQ@EAAF he results of the (t of ∆h for three smples with di'erent sustrte tempertures re shown in tle SFPF le SFPX ixtrted prmeters for islnd growth simultion using geometril model of hemispheril islnds for three smples with di'erent wter )ows during evh oxidnt pulseX HFT smD PFT smD nd TFH smY sustrte temperture ws IPH • gF por simultion using geometril model of hemispheroidl islnds we hoose the vlue GP C in.isl. = 0.05nm.cy -1 F r 2 y )ow @smA HFT PFT TFH ∆r @nmA HFPP HFPQ HFPV @nm -1 .cy

(n) = (1/2R) × (n -n shif t ) 2 D
where n is the evh yle numerD n shif t is the yle numer t whih the islnd growth eginsD nd R is the rdius of urvture of the proli qg urve @Phase IA t point n = n shif t F e (tted the region of the qg etween two lue dshed lines @pigsF SFQ@EAA using n eqution QFQID R nd n shif t vlues otined from the (t re shown in tle SFPF unowing the two prmeters R nd ∆h = ∆rD we n lulte the verge distne b etween hemispheril islnds @∆h = ∆rA using the eqution QFPPF he vlues of the islnd density @N d AD lulted from the verge distne b s 1/b 2 D re shown in the tle SFPF sing extrted ∆hD RD nd n shif t prmetersD we simulted qg urves ordE ing to the geometri growth model of hemispheril islnds @solid red line in (gures SFQ@dEfAAF st is lso possile to hnge the mximum height of the qg pek lose to the experimentl vlues y hnging the islnd spet rtioD i.e. the rtio etween the islnd height nd rdius of the its seD α in.isl. D when GP C = GP C in.isl. D i.e. t the onset of the Qh growthF eny qg vlue nd orresponding yle numer n in hse s @efore the qg mximumA n e hosen s qg in.isl. @n in.isl. AD then qg should e simulted from yle numer n in.isl. F por 4TFH!sm4 smpleD we hoose the vlue GP C in.isl. = 0.05nm.cy -1 D nd hnged the α in.isl. vlue so tht the pek height of simulted qg ws lose to the experimentl qg @simulted qgX green solid line in pigure SFQ@fAAF he α in.isl. vlues for the three smples re shown in le SFPF pigures SFQ@dEfA tht the simulted qgs repet the shpe of the experimenE tl qgs to the left of the qg mximum @on Phase IAF por 4HFT!sm4 nd 4PFT!sm4 smples @(gF SFQ@dA nd SFQ@eAAD the qg mximum heights of the simE ulted nd experimentl qg re the sme when model hemispheril islnds is used @α in.isl. = 1AF por 4TFH!sm4 smpleD the pek heights of the simulted nd experimentl qg re the sme when the rtio initil hemispheroidl islnd rtion is redued to α in.isl. = 0.2F roweverD the vlue of the spred of experimentl qg for 4TFH!sm4 smple is omprle with the di'erene in the height of the pek of the simulted qg using the hemispheril @α in.isl. = 1.0A nd hemispheroidl @α in.isl. = 0.2A islndsF he shpe of the mximum of the simulted qg for three smples @pigF SFQ@dEfAA is slightly di'erent from the shpe of the experimentl qgD ut then ll the qg simultions mth with the experimentl qg in the stedy growth regionF 5.2.3 Analysis of the surface and uniformity of the samples e used etomi pore wirosopy @epwA to investigte the surfe roughness of 4PFT!sm4 nd 4TFH!sm4 smplesF pigures SFR@A nd SFR@dA show two epw imges otined in the tpping mode using fruker himension son etomi pore wirosope T M F he (gures show the presene of (ne grins @see inserts on (gures pigure SFRX epw nd ih results otined for the two smples grown with di'erent wter )ows during oxidnt pulseX PFT sm @4PFT!sm4 smpleA nd TFH sm @4TFH! sm4 smpleAF epw imges otined in the tpping mode for @A 4PFT!sm4 nd @dA 4TFH!sm4 smplesFower petrl hensity @hA funtions lulted from the epw imgesX @A 4PFT!sm4 nd @eA 4TFH!sm4 smplesF @A nd @fA heE pendenes of the nG@nCqA @rossed tringlesA nd nG@nCesA @rossed irlesA )uoresene intensity rtios for two 1 × 1 cm 2 smplesD mesured t di'erent points loted on the sme line for @A 4PFT!sm4 nd @fA 4TFH!sm4 smplesF hese lines re perpendiulr to eh other @tringles nd irles re rossed long or rossAF SFR@A nd SFR@dAAD ut the surfe s whole is smoothF enlysing the epw imgesD we lso lulted the surfe roughness @it is shown in pigsF SFR@A nd SFR@dAAF he surfe roughness w @ q A of 4PFT!sm4 nd 4TFH!sm4 smples re IFI nd IFQ nmD respetivelyF o nlyze the period of irregulrities on the surfeD we used the ower petrl hensity @hA funtionF pigures SFR@EeA show h funtion distriution luE lted with the two smple surfe imgesF he mximum of the frequenies of the h funtions orresponds to n osilltion period of out SHETH nmF st n e seen tht the peks of the h funtions re quite rodF his my e explined y rod islnd size distriution or disordered islnd positionsF es n e seen from (gures SFR@A nd SFR@dAD the ny lyer is omprised of smll grins @or islndsAF yne n resonly identify the vlues orresponding to h pek mximum to the men nerest islnds distneF sf we ompre the verge distnes otined s result of the simultion using hemispheroidl islnd model for these smples @out IH nmAD then these vlues re in the sme order of mgnitude with the most prole vlues of the h funtions @SHETH nmAF e lso heked the homogeneity of the n ontent in the smples y mesuring the Ery )uoresene signl indued y eletrons in nning iletron wirosope @iwA y inergyEhispersive Ery @ihA detetorF sf we selet n eletron energy of Q keD we n oserve the n v α intensity pek from the ny lyer nd q v α nd es v α intensity peks from the snqes sustrte in the )uoresene spetrumD we de(ned integrted intensity of this peks s nD q nd esD respetivelyF et this energyD nd with ny lyer thikness of out IP nmD the nG@nCqA rtio is pproximtely HFUF pigures SFR@EfA show the dependene of the nG@nCqA @rossed tringlesA nd nG@nCesA @irlesA rtios for two 1 × 1 cm 2 smplesD mesured t di'erent points loted on the sme lineF e mesured the )uoresene signls long two lines pssing through the enter of the smple nd prllel to the smple edges @see inserts on (gures SFR@A nd SFR@fAAF hese lines re perpendiulr to eh other @in pigsF SFR@EfA tringles nd irles re rossed long or rossAF st n e seen tht the n )uoresene signl is homogeneous over the entire surfe of the smpleD nd the nG@nCqAD nG@nCesA spet rtios re higher for 4TFH!sm4 smple thn for 4PFT!sm4 smpleF his indites tht t (xed density of zin oxide the ny lyer of 4TFH!sm4 smple is thiker thn ny lyer of 4PFT!sm4 smpleF

Discussion

gompring qg urves for the three smple growth onditionD i.e. with di'erent vlues of the wter )ow during the evh proess @pigF SFQ@dEfAAD we n see tht the rise of the experimentl qg urve ours erlier for smples grown with higher wter )owsF es shown in le SFPD the n shif t vlue is equl to PSyD PHyD nd IRy for the smples grown with wter )ows during oxidnt pulse equl to HFT smD PFT smD nd TFH smD respetivelyF ine the retor hmer is losed during the oxidnt pulseD for given pulse durtion @40sA lrger wter )ow rings more r 2 y Chapter 5. Synchrotron in situ studies, part II (ID3-ESRF) moleules onto the surfeF por lrger numer of r 2 y moleulesD the proility of retion of r 2 y moleule with the smple surfe inresesD nd s resultD greter numer of tive surfe sttes ppers @likely hydroxyl groupsA tht will ret with the hin moleulesF tedy growth per yle @qgA vlues @in le SFPD they orrespond to the ∆r vluesA re firly lose for the 4HFT!sm4 nd 4PFT!sm4 smples @HFPPEHFPQ nmAD insted it is higher for the 4TFH!sm4 smple @HFPV nmAF he qg vlue for smple TFH sm is equl to the idel lyerEyElyer vlue for nyD then it is possile tht for high oxidnt )ow vlueD gh mode ontriutes to growthF epprentlyD in our seD when purging time is (xedD it is possile to derese the vlue of inution ylesD efore growth rte @qgA riseD if the )ow of the wter pulse is higherD up to ertin vlueF enlysis of the experimentl growth per yle urves showed tht it is possile to simulte qg whih repets experimentl dt using model of hemispheril islnds with n verge distne of out IH nmF he n )uoresene mesurements in iw mirosope shows tht the ontent of n toms ross the surfe of the 4TFH!sm4 smple is higher thn for the 4PFT! sm4 smpleD whih orreltes with the ft tht the ny thikness is higher in the 4TFH!sm4 smple thn for the 4PFT!sm4 smpleF 5.3 Substrate temperature variation he sustrte temperture is n importnt prmeter 'eting hemil retions on the smple surfe during evh proess uurunen PHHSF sn the temperture rngeD lled the evh windowD the growth per yle @qgA is onstnt in the stedy stte of growth region qeorge PHHWF sn the hpter R nd in the previous setion SFP it ws shown tht the trnsient regime of ny growth on snqes preedes the stedy growth regimeF husD it is interesting to investigte the e'et of the sustrte temperture on the ny evh on snqes in the trnsient region for tempertures oth in the evh window nd outside the evh windowD sine the growth of ultrthin ny lyers ours in this regionF e investigted the dynmis of this growth for three tempertures @IPH • gD ITH • gD nd PHH • gA in the evh window qo PHITF e denote this smples s 4IPHg4 smple @for sub. =IPH • gAD 4ITHg4 smple @for sub. =ITH • gAD nd 4PHHg4 smple @for sub. =PHH • gAF huring evh proess we used n@g 2 r 5 A 2 or diethylzin @hinA s metl preursorD wter @r 2 yA s n oxidntD nd nitrogen @x 2 A s purgE ing gsF por eh evh yleD the )ows of hin nd r 2 y were S sm nd PFT smD respetivelyY the hin nd r 2 y pulse durtions were S s nd RH sD respetivelyF he x 2 )ow @IHHH smA ws injeted etween hin nd r 2 y pulses during RS s through retor hmer to the pump @retor hmer vlve ws openAF pluoresE ene of n u α nd Ery di'rtion were mesured etween evh yles in situD Ery mesurements for the seleted yle numer were rried out fter oxidnt pulse purgingF huring the mesurements x 2 )ow ws set to IHH sm nd the time required for the mesurements ws from severl minutes to severl hoursF enother smple ws grown with sustrte temperture equl PRH • g @i.e. outE side of evh windowAD we denote this smple s 4PRHg4 smpleF por tht one we mesured the n u α p signl during the entire evh proessF he Ery emD whih energy ws IHkeD impinged on the smple surfe in grzing inidene durE ing ll stges of the evh yle @during hemil retions on the smple surfe with the metlli preursorD oxidnt nd during purgingAF efter the evh ws omE pletedD we mesured inEplne sttering @inEplne reiprol spe mpsA y using fst snning mode @zpEsns or )yEsnsD see efF oool PHISA nd Ery re)etivity @A urve for ll smplesF 5.3.1 Monitoring ALD in situ during the growth por the three smples @ sub of IPH • gD ITH • gD nd PHH • gAD n Ery )uoresene @pA signl ws mesured fter every two evh ylesF pigures SFS@EA show the urves @lue rosses onneted y lineA for three smples with di'erent sustrte tempertures during the evh proessD the logrithm of the intensity is plotted s funtion of the length of the wvevetor trnsfer | q|F e rried out pigure SFSX @AE@AX urves @lue rosses onneted y lineA for three smE ples otined with di'erent sustrte tempertures during evhX @A IPH • gD @A ITH • gD nd @A PHH • gY fest (ts urves otined y using veptos softwre @solid redADF @dAE@fAX verge thikness @hikness@pAA urves versus the numer of yles otined fter lirtion with the resultsD using point for IHH yles @(nl thiknessAY fest (ts in the stedy growth region using liner funtion @red solid linesA the (t of urves using veptos softwre @solid red lines in pigsF SFS@EAAD nd determined the ny thikness nd roughnessY the ny density ws (xed during the (t to the density of morphous nyF he thiknesses @respF roughnessesA of the ny lyers otined y the (ts re IPFR nm @respF IFU nmAD IPFR nm @respF IFU nmA D nd IIFT nm @respF IFT nmA for smples grown t IPH • gD ITH • g nd PHH • gD respetivelyF ine the n )uoresene signl is proportionl to the mss frtion of n toms @or numer of n toms per volume unitAD the p lirted in thikness orE responds to n equivlent thikness s funtion of the numer of ylesF por lirting the p signlD we divided the p vlues y the one otined t yle IHHF henD we multiplied the p vlues y the thikness vlue otined from the (t t yle IHHF pigures SFS@dEfA show equivlent thikness @hikness@pAA versus the numer of yles for the three smples otined with di'erent sustrte tempertures @IPH • gD ITH • gD nd PHH • gAF es n e seen from the (gureD the (nl thikness vlue for the three smples is quite similrD the di'erene is HFV nm t yleF st n e seen thtD (rstlyD the equivlent thikness@pA inreses very slowlyD up to QHERH ylesD then it inrese fster nd nonlinerlyD nd (nllyD rehes onstnt rte of inreseF por detiled nlysis of the equivlent thikness rte of inreseD we plot the growth per yle @qg@pAA funtionsD whih show the inrese in thikness per yleF pigures SFT@EA @pointsA show the experimentl qg@pA for the three smples grown with di'erent sustrte temperturesX IPH • gD ITH • gD nd PHH • gF ih of the three pigure SFTX glulted experimentl qg@pA for three smples with di'erent sustrte temperturesD @A IPH • gD @A ITH • gD @A PHH • gY nd qg urves simuE ltions using either model of hemispheril islnds @green solid linesA or hemiE spheroidl islnds @red solid linesAF qgs is onstnt nd lmost equl to H up to PHEPS ylesF woreoverD one n see tht the vlue of the qg is higher fter the (rst yle ompred to other vlues in this regionF his is likely due to n higher numer of hin moleules rets with sn 0.53 q 0.47 es surfe during the (rst evh yle ompred to next yles in this qg regionF hen the qg funtions inreseD reh mximumD possily derese @indistinguishle due to noiseAD nd tends to onstnt vlueF his qg ehvior orresponds to sustrte inhiited growth type ss or islnds growth mode uurunen PHHRF o extrt some prmeters from experimentl qgD we n simulte qg funE tion y pplying our geometri growth model for hemispheroidl islndsD desried in hpter QF e represent the growth of hemispheril islnds loted in squre grid with period bF he inrement of the hemispheril islnd height per yle @∆h = ∆rA is the slope of the thikness funtion in the liner region orresponding to the stedy growth @lyerEyElyerA euse simulted qg tends to this vlueF e (tted the three thikness urves y liner funtions in the region etween UH nd IHH ylesF he results of the (t ∆h for the three smples otined with di'erent sustrte tempertures re shown in tle SFQF le SFQX ixtrted prmeters for islnd growth simultion using geometril models of hemispheril nd hemispheroidl islnds for the four smples otined with di'erent sustrte tempertures @IPH • gD ITH • gD PHH • gD nd PRH • gAY wter )ow ws PFT smF por the smple grown t PRH • g @see setion SFQFPAD the E ry ws inside the retor hmer during the entire proess of evh @BAF por simultion using geometril model of hemispheroidl islnds we hoose the vlue GP C in.isl. = 0.05nm.cy -1 F sub. @ • CA IPH ITH PHH PRH * ∆r @nmA HFIU HFIV HFIT HFPP @nm -1 .cy

3 A IRQU IITH IHUQ IIUU n shif t @yA IVFH IVFH PPFQ IWFI @nmA WFS WFQ UFP IPFV x d @10 -2 nm -2 A IFI IFP IFW HFT α in.isl.
HFP HFQ IFH HFI sn the simplest seD if the islnds re hemispheresD then it is possile to (t the experimentl qgs in Phase I @see (gure QFRA y the eqution QFQIX GP C(n) =

(1/2R) × (n -n shif t ) 2 D where n is the evh yle numerD n shif t is the yle numer t whih the islnd growth eginsD nd R is the rdius of urvture of the proli region of qg @Phase IA t point n = n shif t F e (tted the region of the qg etween two lue dshed lines @pigF SFT@EAA using n eqution QFQID R nd n shif t vlues otined from the (t re shown in the tle SFQF unowing the two prmeters R nd ∆hD we n lulte the verge distne b etween hemispheril islnds @∆h = ∆rA using the eqution QFPPF he vlues of the islnd density x d D lulted from the verge distne b s 1/b 2 D re shown in le SFQF sing ∆hD RD nd n shif t prmetersD we simulted qg urves ording to the geometri growth model of hemispheril islnds @solid green lines in (gures SFT@EAF st is lso possile to hnge the qg pek height @Phase IIA of the y hging the islnds spet rtio etween the height nd rdius of the islnd9s se α in.isl. when GP C = GP C in.isl. F eny qg vlue nd orresponding yle numer n in hse s @efore the qg mximumA n e hosen s qg in.isl. @n in.isl. AD then qg should e simulted from yle numer n in.isl. F e hose the vlue GP C in.isl. = 0.05nm.cy -1 D nd hnged the α in.isl. vlue so tht the pek height @mximum qg vlueA of simulted qg ws lose to the experimentl qg pek height @simulted qgX red solid lines in the (gures SFT@EAAF he α in.isl. vlues for the three smples re shown in le SFQF es we n see from the tleD for three tempertures in the evh window qeorge PHHWD the vlue of the n shif t is in the rnge of IVEPP ylesF his mens tht for ll three temperturesD the sustrteEinhiited growth of type P phse sttes pproximtely t the sme yle numerD fter whih qg strts to inrese s funtion of yle numerF he experimentl qg vlues for this three smples in stedy stte of growth region re in the HFITEHFIVnm rngeD these vlues re lose to the experimentl qg for the evh window tempertures when hin nd rPy preursors re used for ny evh s shown in efF qo PHITD quziewiz PHIPF he verge distne etween islndsD otined from the hemispherilEislnd model vries from U to IH nmF ht orresponds to the islnd density out IEP islnds per IHH nm 2 F gompring the qg urve simultions otined using the model of hemispheroidl islndsD we n see tht the pek heights of the simulted nd experE imentl qg re the sme when the spet rtio is redued @for the lower the initil roughnessAF imulted qgD using the model of hemispheroidl islndsD repets the shpe of the experimentl qg funtion within the noise of the experimentl dtF 5.3.1.1 In-plane reciprocal space maps huring evh of the three smples otined with sustrte tempertures of IPH • gD ITH • gD nd PHH • gD we mesured inEplne zpEsns @inEplne reiprol spe mps @wAAF hey were rried out only for some evh ylesD t n inidene nE gle of 0.25 • F he Ery em energy ws PH keF e Ph pixelsEdetetor ws used @wxipix T M AF es resultD we otined Ph imges of the sttered intensity s funtion of oordintes h nd k in the reiprol spe of the sn 0.53 q 0.47 es uE i lttieD using fsxoulrs dt redution nd nlysis softwre desried in efF oool PHISF pigure SFU shows some of the inEplne reiprol spe mps for the three smples mesured fter di'erent evh growth yle numersF sn eh of the (guresD one n notie intensity from 220 sn 0.53 q 0.47 es di'rtion pekF e see tht for higher evh yle numersD when the ny lyer eomes thikerD di'rE tion rings egin to pperD s in the se of powder di'rtionF his shows tht rndomly oriented rystllites ppered in the ny lyer with the inrese of the lyer thiknessF o identify the ny peksD one n lulte the rdius of the di'rtion ringsD whih is inversely proportionl to the interplnr distnes for ny lttie plnesD nd y using the referene sghh dt se @hpX HHEHQTEIRSIAD (nd the willer indexes of the ny plnesF o sttistilly improve the signlEtoEnoise rtioD we integrted the intensity vlue of the inEplne w over the ngleD when the rdius ws (xedD nd then found the verge intensity vlue for eh rdius round the r of the ringF por thisD eh point in the grtesin oordintes in the mtrix (h, k, Intensity) used to plot (gure SFU hs een relulted into polr oordintes (ρ, ϕ, Intensity)F henD for eh rdius ρD the verge Intensity over the ngle ϕ @round the r of the ringA ws lultedF e hose the step to hnge the rdius ρ s ∆ρ = ∆h/ √ 2D where ∆h = ∆kD re the step in h nd k in the grtesin oordintesF he dependene of the Intensity on the rdius ρ n e trnsformed pigure SFUX e series of sns for smples with di'erent sustrte tempertures during the evh proessF Ph mps show the dependene of the intensity versus the vlues of h nd k indies in the reiprol spe in oordintes of sn 0.53 q 0.47 es reiprol lttieF ell sns re plotted on the sme sle for intensity @the rinow sle ws usedX purple orresponds to low intensityD red to high intensityAF into dependene of the Intensity on the interplnr distne d using the equtionX

1 d = ρ a In 0.53 Ga 0.47 As , @SFVA
where a In 0.53 Ga 0.47 As is the lttie prmeter of sn 0.53 q 0.47 es @a In 0.53 Ga 0.47 As = 0.586nmAD ρ = √ h 2 + k 2 F le SFR shows the stndrd reltive intensities of ny di'rtion peksD the orresponding interplnr distnes dD nd willer indies (h, k, l)F gompring the vlues of the interplnr distnes d hkl with the position of the di'rtion peksD one n determine the willer indies (h, k, l) for eh pekF pigures SFV@EA show the dependene of the intensity on the interplnr disE tne d otined y integrting the di'rtion rings over the ngle ϕ nd using the eqution SFVF yne n see the presene of three di'rtion peks @see tle SFRAX the most intense 101D nd two less intense 100 nd 002F he positions of the peks re very lose or equl to the referene positionsD inditing tht the ny grins re relxedF pigures SFV@dEfA show Qh plots of the Intensity(d, n) versus interplnr disE tnes d mesured fter di'erent numers of evh yles nF por lower numer of evh ylesD the di'rtion peks re wekly indistinguishle or sentF henD s the numer of evh yles inresesD the di'rtion peks egin to pperF o deE termine the yle numer or thiknessD when the di'rtion peks egin to pperD we (tted Intensity(d) di'rtion urves y three erson type ss funtionsF he kground of Intensity(d) di'rtion urves ws extrted efore the (tF pigure SFW @pointsA shows n exmple of the integrted intensity of the 101 pek versus the thikness of ny lyer for the smple with sustrte temperture PHH • gF sntegrted intensity for evh yle n ws otined from the (t of Intensity(d) frgg peksF pigure SFWX sntegrted intensity @pointsA of the 101 pek versus the thikness of ny lyer for the smple grown t PHH • g nd the est (t y using liner funtion @lineAF he thikness for yle numer n n e found from hikness@pA urve @pigF SFS @fAAF he intensity of the 101 di'rtion pek inreses linerly with inresing ny lyer thiknessF husD we (t the dependene of the 101 di'rtion pek intensity nd pro(le versus yle numer @or thiknessA y stright lineF his liner funtion rosses the xis of thikness t vlue pproximtely equl to P nmF his indites tht di'rtion peks re sent for ny lyer thikness up to P nmF por the three smples grown with di'erent sustrte temperturesD the equivlent thikness of P nm orresponds out to the yle numer t whih the qg rehes its mximumF sn the se of islnd growthD the mximum of the qg pproximtely orresponds to the eginning of islnd oleseneD the grin size hs inresedD the di'rtion peks eome oservleF st is worth noting tht the Ery sorption t the n uE edgeD whih is sensitive to shortErnge order symmetryD shows tht ny hs lredy urtzite struture when the ny lyer thikness is out I nmF 5.3.2 Live measurements during ALD at 240 • C por the smple grown t PRH • g @out of the temperture evh windowD see efF qo PHITD quziewiz PHIPAD we mesured the n u α )uoresene signl during the whole evh proess @not only during purging steps etween yles in ontrst to wht ws done for the three smples grown t IPH • gD ITH • gD nd PHH • g @in temperture evh windowAAF pigure SFIH@A shows the mesured n p signl s funtion of the yle numer t growth temperture equl to PRH • gF yne n oserve hrteristi jumps on the p urveX the p intensity signl shrply inreses t the eginning of eh yle when the n preursor is injeted into the retor hmer nd dsor on the smple surfeF snitillyD the intensity inrese of the n p signl ours omprtively slowly @the growth rte is out IH times smller thn in the stedy growth regionA nd is linerD then inresing yle numerD the p intensity ehves nonliner prior to eomes linE er @stedy growthAF sn omprison with the growth t lower tempertures @in the pigure SFIHX @A n uα Ery )uoresene @pA signl s funtion of the yle numerD @A equivlent thikness dependeneD hikness@pA versus yle numE erD otined y using thikness of IT nm t IHH yles @from AD @A lulted experimentl qg@pA nd qg simultion urves using model of hemispheriE l islnds @green solid linesA nd model of hemispheroidl islnds @red solid linesAF he growth temperture ws PRH • gF temperture evh windowAD in the rnge IEPH yles one oserves the deposition of nEontining mterils together with notiele desorption of nEontining moleulesF nfortuntelyD s in the se of the three smples grown t lower temE pertureD the signlEtoEnoise rtio of the n p intensity inreses together with the inresing of the p intensityF e otined the (nl thikness vlue of the ny lyer y (tting the Ery re)etivity @A urve mesured fter the ompletion of IHH evh yles @the E ry em energy ws PH keAD it is out IT nmF he verge ny lyer thikness eing proportionl to the n p signl @ssuming onstnt lyer densityAD we used this (nl thikness vlue to lirte the p urve nd plot it s thikness urve @hikness@pAAF pigure SFIH@A shows the equivlent thikness dependeneD hikness@pAD s funtion of the yle numer for the smple grown t PRH • g he n p intensity vlues were verged inside eh yleD onsequentlyD in pigure SFIH@A only one point orresponds to one yle numerF pigure SFIH@A shows tht the qg@pA orresponds to sustrte inhiited growth of type ssD i.e. Qh islnding @rougheningA efore stedy liner growth rteF epplying the geometri model of hemispheril islndsD we simulted the whole qg urvesD using extrted prmeters from experimentl qg@pAF o deterE mine the qg @is equl to ∆r = ∆h for hemispheril islndsA in the stedy stte of growth @liner ehvior eyond the trnsient regimeAD we (tted the hikness@pA urve in the liner region etween UH nd IHH yles y liner funtion @red solid line in pigF SFIH@AAF he rdius R nd n shif t vlues were determined y (tting of the qg@pA experimentl plot in hse s region @onset of the Qh islnd growthAF he ∆r = ∆hD RD nd n shif t vlues re shown in le SFQD thenD they were used for the whole qg urve simultionsF sn the (gure SFIH@AD the green solid line is the qg urve simultion using the hemispheril islnd modelF elthough the dt is quite noisyD the qg pek height looks to e overestimtedF fy hnging the spet rtio α in.isl. etween the rdius nd the height of the islnd for (xed qg vlue @for instne GP C in.isl. = 0.05nm.cy -1 AD we redued the height of the qg pek @red solid line in the pigF SFIH@AAF ell the prmeters used for simultion re shown in the tle SFQF pigure SFII@A shows the w @otined with zpEsnsA mesured t the end of the evh proess for the smple grown t PRH • gF yne n see the presene of pigure SFIIX @A pEsn mesured fter IHH evh yles nd @A the dependene of the verge intensity on the interplnr distne d for the smple grown t PRH • gF powder di'rtion ringsD whih is inditive of the presene of rndomly oriented rystllites in the plne of growthF prom the wD we verged the sttered intenE sity over the ring rs nd onstruted Ih dependene urve of the intensity upon the interplnr distne d @(gF SFII@AF henD fter removing the kground we (tted eh di'rtion pek y erson ss funtionF st n e seen tht the 002 di'rtion pek hs eome less intense thn the other two peksD in omprison with the other growth tempertures @see tle SFR nd pigF SFVAF his indites tht inresing the growth temperture fvor the preferred orienttion long the Exis @the HHP diretionA foihot PHITF rowever omplete texture nlysis would only e possile y mesuring ole (guresF 5.3.3 Analysis of the surface and uniformity of the samples e used etomi pore wirosopy @epwA to investigte the surfe relief of the four smplesD for whih di'erent sustrte temperture ws used @IPH • gD ITH • gD PHH • gD nd PRH • gAF pigure SFIP shows four epw imges otined in the tpping modeF he (gures show the presene of (ne grins @see the insets of (gures SFIP@EdAAD ut the surfe s whole is smoothF o nlyze the period of irregulrities on the surfeD we used the ower petrl hensity @hA funtion s ws lredy desried in setion SFPFQF pigures SFIQ@EdA show h funtion distriution lulted for epw imges for this smplesF he h funtions repet the sme ehvior s for the smples desried in the setion SFPFQF he mximum of the frequenies of the h funtions orresponds to n osilltion period of out RHETH nmF hese vlues re in the sme order of mgnitude with the verge distnes otined s result of the simultion using hemispheroidl islnd model @out IH nmAF pigure SFIPX epw imges otined in the tpping mode fter evh @IHH ylesA for the smples grown t @A IPH • gD @A ITH • gD @A PHH • gD nd @dA PRH • gF pigure SFIQX ower petrl hensity @hA funtion otined from epw imges reorded for the smples grown t @A IPH • gD @A ITH • gD @A PHH • gD nd @dA PRH • gY nd surfe roughness @wA of this smples @eA prom the epw imgesD we lso lulted the surfe roughness w @ q A nd the rithmeti verge of the solute vlues of the surfe height devitions mesured from the men plne @ a A @pigF SFIQ@eAAF he surfe roughness of four smples is out I nmD whih my e due to the presene of (ne ny rystllitesF e lso heked the homogeneity of the n ontent s desried in setion SFPFQF pigures SFIR@EdA show the dependene of the nG@nCqA @rossed tringlesA nd nG@nCesA @irlesA rtios for two 1 × 1 cm 2 smplesD mesured t di'erent points loted on the sme lineF st n e seen tht the n )uoresene signl is slightly pigure SFIRX hependenes of the nG@nCqA @rossed tringlesA nd nG@nCesA @rossed irlesA )uoresene intensity rtios for two 1 × 1 m smplesD mesured t di'erent points loted on the sme line for the smples grown t IPH • g @AD ITH • g @AD PHH • g @AD nd PRH • g @dAF hese lines re perpendiulr to eh other @tringles nd irles re rossed long or rossAF higher lose to the enter of the smpleD proly in the position of the Ery em during in situ mesurementsF his n e used y slight in)uene on the ny evh growth in the ple of the smpleD where the Ery intertsF es generl trendD the )uoresene signl is homogeneous over the entire surfe of the smpleF his indites the homogeneity of ny t ll smple pointsF por the three smples for whih the sustrte temperture during evh ws in the evh temperture windowD the nG@nCqA spet rtio is pproximtely the sme @out HFUAF his result is in greement with the ft tht the (nl thikness of the ny (lm for these smples lso the sme @out IP nmAF por smple with sustrte temperture of PRH • gD the )uoresene spet rtio nG@nCqA is higher @out HFVA then for other smplesD nd this orreltes with the ft tht the thikness for this smple is lso higher @out IT nmAF 5.3.4 Discussion e see in tle SFQ tht the qg vlue in the stedy stte of growth region @in the tle they orrespond to the ∆r vluesA is firly similr for smples grown t IPH • gD ITH • gD nd PHH • gF elsoD the yle numer whih orresponds to qg inrese is lmost the sme for three smples @n shif t = 18 -22cyD see F SFQAD nd oinides with the yle numer whih orresponds to qg inrese for the smple for whih the sme experimentl onditions were used @T sub. = 120 • CD r 2 y )ow ws PFT smAD ut the Ery em ws impinging on the smple surfe during ylesD i.e. during hemil retions @n shif t = 20cyD see tF SFPAF his mens tht the sustrte temperture in the IPH • gEPRH • g rnge lmost does not 'et the yle numer n shif t orresponding to the eginning of the qg inrese @eginning of the sustrteEinhiited growth of type PAF es ws shown for the 4PHHg4 smpleD the ny Ery di'rtion peks egin to pper when the thikness of the deposited mteril is higher thn P nmF gompring the thikness nd qg urves for the 4PHHg4 smpleD one oserves tht thikness equl to P nm orresponds to the eginning of the islnd9s olesene @mximum of the sustrteEinhiited qg urveAF husD when the thikness inreses @strting from the oleseneAD the grin size inresesD nd the longErngeEorder of the ny urtzite struture is deteted y Ery di'rtionF st is interesting to noteD s ws shown in hpter RFQFRD ny urtzite struture is evidened y Ery sorption for lower ny (lm thikness @∼I nmAD elow tht vlue the mteril is morphousF he (nl ny thikness nd n ontent t di'erent points of the smple is pproximtely the sme for the smples grown with the sustrte temperture in the ny evh window @for the 4IPHg4D 4ITHg4D nd 4PHHg4 smplesAF st is interesting to note tht the qg vlues oserved in the stedy growth regime re higher for the 4PRHg4D 4HFT!sm4D 4PFT!sm4 nd 4TFH!sm4 smples @see tle SFPA thn for the 4IPHg4D 4ITHg4D nd 4PHHg4 smples @see tle SFQAF yne n think of two resons for explining the di'erene in stedy growth qg for this smplesF he (rst reson is tht we used di'erent methods to lirte the )uoresene signl for two groups of smplesX for 4HFT!sm4D 4PFT!sm4D nd 4TFH!sm4 smples we used thikness otined from the re)eted em intensity osilltions versus yle numerD instedD for 4IPHg4D 4ITHg4D 4PHHg4D nd 4PRHg4 smples we used the thikness otined from the (t of Ery re)etivity urvesF his hypothesis is eing heked with mesurements performed with the 4HFT!sm4D 4PFT!sm4D nd 4TFH!sm4 smplesF he seond hypothesis ould e tht the mesurements for the 4HFT!sm4D 4PFT!sm4D 4TFH!sm4D nd 4PRHg4 smples were rried out with the Ery em impinging ontinuously onto the smple surfe during hemil retionsD insted for the 4IPHg4D 4ITHg4D nd 4PHHg4 smples the Ery em interted with the smple surfe only during the purge in x 2 tmosphere etween ylesF hen one ould think of em e'et tht would hve enhned the hemil retionsF roweverD nG@nCqA )uoresene spet rtio mesurements on iw shows tht the zin ontent in 4PFT!sm4 nd 4IPHg4 smples is out the smeF ine the growth onditions for these two smples were the smeD nd only the method of mesurement ws di'erentD we n onlude tht the Ery em hs prtilly no e'et on growth for this smplesF por ll grown smplesD the surfe roughness w fter IHH yles re reltively smll @out I nmAD whih is lower thnD for instneD surfe roughness of ny grown on i nd qx sustrtes @see efF fji PHIPAF he zin oxide lyer is lso homogeneous over the entire surfe @IxI m 2 A of the smple for ll mesured smplesF es shown in the (gure SFIID the 002 di'rtion pek is less intense ompred with the referene intensity of ny @see tle SFRAD whih indites the pperne of the wellEknown preferred orienttion for ny grins with the @HHIA plnes prllel to the sustrte surfe foihot PHITF his orienttion is fvored y the low energy of the @HHIA surfe when sreened pujimur IWWQD ujikw PHHTF

Conclusion

e showed tht the hnge in the thikness of the deposited ny lyer n e monE itored y mesuring the intensity of re)eted Ery em @t low inidene ngleA s funtion of the yle numerF e used the otined thikness to lirte the n )uoresene signl mesured during ny evh to plot the equivlent thikness versus yle numerF iquivlent thikness nd orresponding qg urves were oE tined for three smples grown with di'erent wter )ows during the evh proessX HFT smD PFT smD nd TFH smF por the three vluesD we oserved regime of very low growth rte @lmost zero qgAD followed y region of sustrteEinhiited growth of type P tht turned into stedy stte of growth @liner growthAF o nlyze the qg urves @representtive of sustrteEinhiited growth of type PD whih is ssoited with islnd growthD or hnge in the roughness in our seAD we used our geometri modelD desried in ghpter QD tht shemtizes the growth of hemispheroid islnds y evhF e showed tht it is possile to simulte the qg urves for the three smples @4HFT!sm4D 4PFT!sm4D nd 4TFH!sm4AD y using hemispheroidl islnds with density of IEP islnds per IHH nm 2 F he numer of yles @or dely timeA needed for the qg to strt inresing @i.e. to strt sustrteEinhiited growth of type PA ws determined for these three smple growthX PSD PHD nd IR yles for the 4HFT!sm4D 4PFT!sm4D nd 4TFH!sm4 smplesD respetivelyF his numer is redued when inresing the wter )ow used during the ny evh on snqesF elsoD we demonstrted for three smples grown with di'erent sustrte temperE tures inside the evh window @4IPHg4D 4ITHg4D nd 4PHHg4 smplesD see susetion IFPFP of ghpter IAD tht longErngeEorder struture is deteted y Ery di'rE tion with the pperne of mirostruture when the thikness of the ny lyer is higher thn P nmF he ny thikness of P nm orresponds to the vlue for whih oth the intensity of the di'rtion peks egins to inrese nd the qg urve rehes its mximum @islnd oleseneAF husD we ssoite the pperne of the inEplne ny di'rtion peks with the ny grins size inreseF e know tht elow tht thikness down to out I nm the ny lyer retins the urtzite struture nd is morphous elowF enlyzing the qg urves for the three smples @4IPHg4D 4ITHg4D nd 4PHHg4AD we found tht the numer of yles prior to the eginning of the sustrteEinhiited growth of type P is lmost independent of the sustrte tempertureF por ll three smples this numer ws IVEPP ylesF elsoD for smple grown with higher sustrte temperture 4PRHg4 @outside the evh windowAD nd (nl lyer thikness equl to IT nm t yle IHHD we lerly oserved the wellEknown ny texturingF he qg vlues in the stedy stge of growth for ll mesured smples re omprle to those otined for the ny evh @see susetion IFPFP of ghpter IAF Ex situD nlysis of the sEgrown smples showed tht the n ontent in the ny lyers is uniform throughout the surfe of 1 × 1 m 2 smplesD nd the surfe roughness is rther smll @out I nm or lessAF Chapter 6

Electrical measurements

In this chapter, we consider the problem of Fermi level pinning for metal/semiconductor contacts and the ways to solve it. In particular for Al/In 0.53 Ga 0.47 As contacts, it was shown that the introduction of a thin ZnO layer in between the Al and In 0.53 Ga 0.47 As (InGaAs) reduces specic contact resistivity ρ c . We used a stencil method and photolithography, to create metal/InGaAs contacts. The ZnO layer was grown by the atomic layer deposition (ALD) technique, which allows to control the thickness of the deposited material and create ultra-thin layers. Using Transfer Length Method (TLM), we measured specic contact resistivity ρ c for series of metal/ZnO/InGaAs samples with dierent ZnO layer thicknesses. Two types of InGaAs samples with two types of conductivity were used: n-type InGaAs (n-InGaAs) and p-type InGaAs (p-InGaAs). Al was used as a metal for contacts for the most of samples, for comparison, we also used Ti for two samples. We demonstrate that the specic contact resistivity value was almost 9 times decreased for Al/ZnO/p-InGaAs sample (with ZnO inserted in between Al and InGaAs), compared to an Al/p-InGaAs sample without ZnO.

Introduction and methods

hue to the redution of wy (eld e'et trnsistor sizeD the ontt resistne of snE qes hnnel reduing eomes importntF st ws shown tht the ontt resistne n e reduedD for instneD y reting metl lloys for snqes onttsF hese lloys re otined using solidEstte retions etween deposited metl nd snqesD lthoughD one should tke into ount the formtion of dditionl phses nd texE turing of the intermetllisD whih n 'et the moility of hrge rriers nd eleE tril prmeters hiou PHITF en lterntive wy to redue metlGsn 0.53 q 0.47 es ontt resistne is introduing thin insulting oxide lyer in etween the metl nd sn 0.53 q 0.47 es @snqesA egrwl PHIPF ny n ply the role of suh insuE ltor for metlGsnqes ontt vio PHIQF he presene of ny introdued into ontt n depinning the permi levelD nd redue the ontt resistne vio PHISF o e'etively trnsfer the urrent into the metlGnyGsnqes onttD the optiml ny lyer thikness should e seletedF he ny lyer hve to e thin enough not to derese the )ow of the tunnel urrentD nd thik enough to redue or prevent the e'et of permi level pinning gonnelly PHHRF rereD (rstD we desript generl se of the metlGsemiondutor nd digrmsD onsider the prolem of the permi level pinning nd its possile solutionsF henD we rie)y desrie the rnsfer vength wethod @vwA methodD whih ws used for determintion of spei( ontt resisE tivityF sn the seond prtD we show experimentl results nd their omprison of the sE urves nd spei( ontt resistivities for the set of metlGnyGsnqes smplesF 6.1.1 Ohmic and Shottky contacts and Fermi level pinning vet us onsider the lssil se of metlGsemiondutor nd digrms whih follow hottkyEwott reltionshipF here exists rule whih predits the semionE dutor energy rrier height in the sene of interfe sttesF pigure TFI@A shows the energy levels of the metl nd nEtype semiondutor pled t distne δ from eh other ung PHHIF he energy levels nd work funtions of the semiondutor re shown on (gures TFIX E v is the energy of the top of the vlene ndD E c is the energy of the ottom of the ondution ndD E i is the permi level of the intrinsi mterilF he level of vuum energy is E vac F he eletrohemil potentil lso lled herefter the permi level energy E F D is equl in oth the metl nd semiondutorF χ = E vac -E c is the vuum eletron 0nity of the semiondutorD nd Φ sc the vuum work funtion of the semiondutorF he vuum work funtion of the metl is Φ m F es the distne etween the metl nd the semiondutor δ deresesD the enE ergy nd of the semiondutor in the ontt region egins to urve @pigF TFI@AAF he height Φ bn ove the permi level E F is the hottky rrier heightD it deE termines the urvture of the semiondutor energy ndF por n in(nitely lrge metlGsemiondutor gp distne @δ → ∞AD the semiondutor energy nd is not urved @Φ bn = Φ sc -χAF hen the distne δ is 0D Φ bn = Φ m -χF Φ bn s funtion of δ is shown on (gure TFI@A for the se when Φ m > Φ sc F pigures TFI@A nd TFI@A show metlGnEtype semiondutor nd digrms nd the sE urvesF es it n e seenD the nd gp energy urvture up or down depends on the reltionship etween Φ m nd Φ sc F sf the vuum work funtion of the metl is higher thn vuum work funtion of the semiondutor @Φ m > Φ sc AD the metlEsemiondutor @wA struture ehves s hottky rrier for eletrons of nEtype semiondutorD nd s n ohmi ontt for holes of pEtype semiondutorF sf the vuum work funtion of the metl is lower thn the vuum work funtion of the semiondutor @Φ m < Φ sc AD the w struture ehves s hottky rrier pigure TFIX @A hemonstrtion of hottkyEwott ruleD the dependene of semionE dutor nd ending s funtion of δ @distne etween the two mterilsAF he hottkyEwott reltionship is otined t zero gp distneF @A fnd digrm of hottky rrier for eletronsX metl nd nEtype semiondutorD Φ m > Φ sc Y nd the urrentEvoltge hrteristi of the wetl hottky rrier @voltge is pplied on the metl sideAF @A fnd digrm of n ohmi ontt for eletronsX metl nd nEtype semiondutorD Φ m < Φ sc Y nd the urrentEvoltge hrteristi of ohmi ontt @voltge is pplied on the metl sideAF for holes of pEtype semiondutorD nd s n ohmi ontt for eletrons of nEtype semiondutorF sn ontrst to the idel se disussed oveD in rel se the semiondutor nd metl ontt n hve surfe sttes oertson PHIQF por exmpleD wetl sndues qp ttes @wsqA pper due to the presene of the wve funtions of eletrons on metlGsemiondutor interfe whih re foridden within the ulk semiondutor gpD ut llowed t the surfeF elsoD hefetEsndued qp ttes @hsqA pper due to the lttie periodiity rek lose to the surfeF fsillyD wsq re more likely to use permi level pinningD euse in most ses the density of wsq is higher thn defet sttes densityF por this resonD permi level of metlGsemiondutor ontt n e pinned in the semiondutor nd gp where density of surfe sttes existsF hen permi level is pinnedD the hottky rrier height is di'erent from the height otined for hottkyEwott modelF por instneD hottky rrier height @frA for eletrons is

Φ bn,ef f = S(Φ m -Φ sc ) + (Φ sc -χ), @TFIA
where is dimensionless hottky pinning prmeterX

S = 1 1 + e 2 N λ εε 0 , @TFPA
rereD e is the eletroni hrgeD x is the density of the interfe sttes per unit reD k is their dey length into the semiondutorD ε is the dieletri onstnt of the semiondutor interfe regionD nd ε 0 is the permittivity of free speF permi level pinning n inrese fr nd inrese ontt resistivityF yne wy to derese the metlGsemiondutor ontt resistivity is to inrese the semionduE tor doping levelF righ semiondutor doping level in the re of ontt redues the width of the hottky depletion region @the width of the hottky potentil rrierA nd the ontt resistne of metlGsemiondutor juntion n e deresedF fesidesD one n lso redue the width of depletion region y deresing the uiltEin voltgeD whih is thought to e relted to the height of hottky frrierF e solution to redue the hottky frrier reight nd thus the interfil ontt resistne is y inserting n ultrEthin insultor lyer in etween the metl nd the semiondutorD to form wetlEsnsultorEemiondutor @wsA system to derese the penetrtion of eletron wveEfuntions of the metl into semiondutorF he ws nd digrmme from efF vio PHIS is shown in pigures TFP@A nd TFP@AF pigure TFPX @A hemti nd digrm nd mehnism for the metlGsemiondutor @wEA ontt nd @A for ws ontt with inserted highE k insultor in etween metl nd semiondutor with surfe sttes vio PHISF unneling through n interfil insultorX @A he nd digrm shows deep sttes fe lrger minimum rrier thn do free rrier sttesD nd thus re more rpidly ttenuted @indited y rrow lengthAD llowing free rriers to tunnel while lokE ing the wsqF @dA he optimum insultor thikness is where the gp sttes re e'etively loked while free rrier tunneling is still su0ient gonnelly PHHRF e highEk dieletri lyer redues the wetlEsnduedEqpEtte @wsqAD depin the permi levelD nd derese the hottky rrier height @frAF gonsequentlyD the ontt resistne is lowerF hen thin insultor lyerD inserted in etween metl nd semiondutorD prevents metl sttes from penetrting into the semiondutor gp nd produing wsq @see (gF TFP@A from efF gonnelly PHHRAF roweverD the tunneling urrent exponentilly dereses with insultor thikness inreseF husD the optiml thikness of insultor lyer should e hosen @see (gF TFP@dA from efF gonnelly PHHRAX the lyer should not e too thin not to llow wsq to penetrte into the semiondutorD nd it should not e too thik to lok trnsport of free rriersF por wetlGemiondutor juntionsD the hottky frrier reight @frA ould e predited y the hottkyEwott modelD if there were no interfe sttesF hen interfe sttes re presentD minimum of ontt resistivity n e rehed with the right omintion of metl nd insultor for given semiondutorF iletron 0nity of sn 0.53 q 0.47 es is out 4.54eV D whih is lose to the work funtions rölzl IWUW of xiD elD iD woD tD dD euD egD grD nd guF vio et al. vio PHIQ demonstrted tht the ultrElow ontt resistivity of 6.7 × 10 -9 Ω.cm 2 otined for elGnyGsnqes@iX 1.5 × 10 19 cm -3 A onttsD using 0.6nm thik ny lyerF tF gF vin et al. vin PHIQ hve frited wetlGsnqes ontts for oth nE nd pEtype snqes with woD t ndD d s ontt metlF he mesured spei( ontt resistivity ws in the rnge 10 -5 Ω.cm 2 nd 10 -8 Ω.cm 2 F vow spei( ontt resistivity etween 10 -8 nd 10 -9 Ω.cm 2 ws otined for nonElloyed ohmi ontts on nEtype sn 0.53 q 0.47 es grook PHHUF hese ontts were formed y oxidizing the semiondutor surfe through exposure to ultrvioletE generted ozoneD susequently immersing the wfer in mmonium hydroxide nd (nlly depositing either iGdGeu ontt metl y eletronEem evportion or i ontt metl y vuum sputteringF e physisEsed uni(ed model demonstrtes tht the low resistivity metlEinsultorE semiondutor @elGinsultorGsn 0.53 q 0.47 esA ohmi ontt n e hnged for difE ferent insultor thikness @pigF TFQ@AA egrwl PHIPF pigure TFQX @A glulted spei( ontt resistivity s funtion of insultor thikE ness for elGinsultorGnEsn 0.53 q 0.47 es with v 2 y 3 D nD neD nyD iy 2 D 2 y 5 D riy 3 D qey 2 D gdyD nd ny 2 s interfil insultorsF @A minimum spei( onE tt resistivity s funtion of optiml insultor thikness from efF egrwl PHIPF glultions show tht ny is one of the est ndidtes for permi level depinE 124 Chapter 6. Electrical measurements ning @pigF TFQ@AAF he minimum spei( ontt resistivity ould e rehed for HFTnm thik ny thin (lmF 6.1.2 TLM measurements yne wy to mesure ontt resistne or spei( ontt resistivity is the line rnsE fer vength wethod @vwA ferger IWTWD wurrmnn IWTWD ferger IWUPD gohen IWVPF his method hs proven its e0ieny in miroeletronis nd is sed on mesuring the resistne etween identil ontts loted on line t di'erent distnesF pirstD we give the si de(nitions tht re used to explin this methodD nd then we will present the method nd the mesurement tehnique itselfF 6.1.2.1 Resistance and resistivity denitions es shown in pigF TFR@AD the resistne of homogeneous ondutor with onstnt rossEsetion SD depends on the properties of the ondutorD its length lD its rossEsetion SD nd is lulted sX

R = ρ × l S , @TFQA
where ρ is the ondutor resistivity @physil hrteristi of the mterilD indepenE dent of rossEsetion nd length of this mteril tht re geometril prmetersAF pigure TFRX hi'erent types of resistne nd resistivity representtionsF @A romogeE neous ondutor with onstnt rossEsetion S nd length lF @A gondutor sheet or thin lyer with ross setion t × W D nd length lF @A wo ontts nd urrent density lines etween these onttsD W is the ontt width nd L t is the trnsfer lengthF

he unit of resistne R is [Ohm] or [Ω]D nd the one of resistivity ρ is [Ω × m]F
por thin lyers of mterilD for whih one geometril length is muh less in one diretion thn in the other two diretions @se of sheetAD it is onvenient to de(ne the sheet resistne R s F pigure TFR@A shows the ondutor sheet or thin lyer with ross setion t × W D where t is the thikness nd W the widthF sf the urrent )ows long the length l of the ondutorD the resistneD lulted ording to the eqution TFQ is

R = ρ × l t × W = R s × l W , @TFRA
where R s = ρ/t is the sheet resistne E the physil hrteristi of lyer of onstnt thikness tF he sheet resistne R s is mesured in Ω/ D where the squre ion indites tht it is the sheet resistne is di'erent from the resistne RF pigure TFR@A shows two ontts nd urrent density lines etween these onE ttsF he urrent )ow through the rossEsetion W × L t D where W is the ontt widthD nd L t is the trnsfer lengthF pei( ontt resistivity ρ c is de(ned s the ontt resistne R c multiplied y the ontt re W × L t through whih the urrent )owsX

ρ c = R c × W × L t , @TFSA
hen the spei( ontt resistivity is mesured in [Ω × cm 2 ] @or [Ω.cm 2 ]AF he tle TFI summrizes the vrious resistnes nd resistivities disussed oveF le TFIX esistne nd resistivity de(nitionsF he(nition

xottion iqution nit of mesurements esistne R = (ρ × l)/A [Ω] esistivity ρ ρ [Ω × m] heet resistne s R s = ρ/t [Ω/ ] pei( ontt resistivity ρ c ρ c = R c × L t × W [Ω × cm 2 ]
6.1.2.2 TLM measurement principle and specic contact resistivity extraction sn trnsfer length method @vwAD four proes re used to mesure the totl resisE tne R tot etween ouple of onttsD s shown in pigure TFS@AF pigure TFSX hemti representtions of vw strutureF ell ontt pds re identil @width W nd length aAD nd seprted y n inresing distne l i_(i+1) F @A hemti representtion of fourEproe eletril mesurementsF @A hemti representtion of the resistnes ontriuting to the overll mesured resistne in vwF sdentil retngulr ontt pds rrnged long stright lineD the distne etween the losest ontt sides of two ontts i nd (i + 1) is l i_(i+1) D where i is the seril numer of ontt pdD i vries from I to the numer of ontts nF fetween the two proes pled on the ontts i nd (i + 1)D potentil di'erene is retedD nd two other proes re used to mesure the urrent )owing etween these onttsF e limittion of vw is tht experimentl sE urves should e ohmi @linerAD the method is not pplile to hottky rriersF sn our work we use the riteri to determine the linerity of the sE urveX if the oe0ient of determintion Esqured of the experimentl s@A funtion is greter thn HFW @lose to IAD we onsider tht this funtion is linerY otherwiseD we onsider this funtion s nonliner nd do not pply vw method to these onttsF sf the mesured sE hrteristi is linerD then it is possile to (t it y stright line nd lulte the totl resistne R tot etween these two onttsD using yhm9s lw s the inverse vlue of the line slopeF henD the proes re moved to the next ouple of ontts (i + 1) nd (i + 2)D nd the proedure is repetedF es resultD we mesure the totl resistne R tot etween the ouples of ontt pds s funtion of the distne l etween these pdsF pigure TFS@A shows sheme of the trnsverse setion of the vw struture on whih the resistnes etween the ontt pds re representedF he totl resistne R tot etween two ontts n e lulted sX

R tot = R c + R sub. + R c , @TFTA
where R c is the vlue of the ontt resistneD R sub. is the vlue of the sustrte inEplne resistneF e rewrite R c nd R sub. to show the sheet resistne y using expression TFRX

R tot = 2R s.c. × L t W + R s.sub. × l W , @TFUA
where W is the ontt widthD L t the ontt trnsfer lengthD R sc nd R s.sub. the sheet resistnes of the ontt nd sustrteD nd l is the distne etween the feEto fe ontt sidesF henD mesuring tot s funtion of the distne etween the onttsD lD nd (tting the experimentl points y the liner funtion given y iqF TFUD one otins 2R c on the R tot xis nd (-2R sc L t )/R s.sub. on the l xis @pigF TFTAF sf we ssume tht R s.c. = R s.sub. D then (2R sc L t )/R s.sub. = 2L t F husD from the (t of R tot (l) experimentl urveD we determine the ontt resistne R c @[Ω]A nd trnsfer length L t @[cm]A vluesF hen the width of onttD W D is knownD one n lulte the spei( ontt resistivity y using the R c nd L t vlues nd eqution TFSF 6.2 Results and discussion 6.2.1 Stencil method and results 6.2.1.1 Deposition of contacts through stencil yne wy to rete metl ontts on the smple surfe is metl deposition with stenilF pigure TFU@A shows shemti whih desries this proessF pigure TFTX hemti representtion of tot @lA urve used to extrt the spei( ontt resistivity in the se of vw experimentF pigure TFUX @A hemti of stenil stuk to the surfe of the smpleF he metl is deposited on the entire smple nd stenil surfe y sputteringX the metl is deposited on the smple surfe not overed y the stenilF @A iture of 75µm thik xi stenil oted with 2.5µm thik iyxF iyx lyer protets xi stenil during ething with idsF he R lines stenil pttern is repeted in two perpendiulr diretions with period of 7mm @the geometri prmeters of these lines re shown on (gF TFVAF pirstD the stenil is stuk to the surfe of the smpleF he stenil hs severl lines with pertures through whih the metl is deposited to rete onttsF he geometri prmeters of the stenil pertures nd the distnes etween them re desried lter in the text of this setion @see pigF TFVAF henD the metl is deposited on the entire of smple nd stenil surfe @(gF TFU@AAF sn ples where the stenil hs pertures E the metl is deposited on the smple surfeD in the remining prts of the stenil E the metl is deposited on the stenil surfeF henD the stenil is pull o' the smple surfeD the metl ontts remining thereF huring the preprtion of the smple nd stenilD it is neessry to )tten nd stuk the stenil to the smple surfe s muh s possileD euse the qulity of mehnil ontt etween smple nd stenil ensures the reproduiility of the 128 Chapter 6. Electrical measurements stenil ptterns on the smple surfeF roweverD using this method for reting metl onttsD gps etween the smple surfe nd the stenil inevitly remin due to lol ending of the stenilF hue to gp in etween the stenil nd smpleD the deposited metl )ow penetrtes through the stenil pertureD reting shdow e'et tht inreses the re of the plnned onttD s it shown on (gure TFU@AF e hve used 75µm thik xi stenil oted with 2.5µm thik iyx otined from the veti @gietehAF iyx lyer is used to protet xi stenil during ething with ids when lening proedure tkes pleF pigure TFU@A shows piture of the stenil nd ptternsF he four line pttern onsists of pertures for the metl depositionD it is repeted ording to 7mm × 7mm squre lttie periodiityF o rete metl ontts on one smple surfeD it is enough to ut out only one 7mm × 7mm pttern @motifA of the stenilF pigure TFV@A shows the geometri prmeters of the pertures of one stenil motifF pigure TFVX @A qeometri prmeters of the pertures of one stenil motifF yne stenil motif ontins four linesD @sD ssD sssD sAF ih line ontins V identil perE tures @ID PD Q etc.AD the distnes etween two neighor pertures inrese for higher perture numersF @A yne piture of el ontts deposited on snqes surfeD otined with n optil mirosope @ywAF flk dshed frmes show the expeted stenil shpe nd size of el onttsF tenil motif ontins four linesD we lel them line sD ssD sssD nd sF ih line ontins V identil pertures @ID PD Q etFAD the distne etween two neighor perE tures inreses for inresing perture numersF he distnes etween neighor pertures reX 50µm etween pertures I nd P @50µm for 12AD 100µm for 23D 150µm for 34D 200µm for 45D 250µm for 56D 300µm for 67D nd 500µm for 78F he size of the pertures for eh line is di'erentX for lines s nd ssD it is squres of size 200µm × 200µm nd 100µm × 100µmD respetivelyY for lines sss nd s E retngulr frmes of size 100µm × 400µm nd 50µm × 200µmD respetivelyF sing stenil with the geometri on(gurtion desried oveD we deposited el ontts y sputtering on series of snqes nd nyGsnqes smples @in this hpterD for revityD we denote sn 0.53 q 0.47 es s snqesAF er plsm with hg voltge ws used for el sputtering in hysil por heposition @hhA gIHH T M hmerF he ny ws deposited on pE nd nEtype snqes y evh using the wyyx retorF pirstD ny ws deposited on the entire snqes surfeD nd then metl ws deposited through the stenilF iven if we performed ny evh with stenil on the smpleD then the ny will e deposited on the entire surfe of the smple under the stenil nd on the stenil itselfF he ny omplete oting of the hemilly retive snqes surfe is possile due to the ft tht the sizes of the metl preursor nd oxidnt moleules re muh less thn the distne etween the snqes surfe nd the stenilF he thikness of ny lyer ws vried @ di'erent numer of yles ws seleted for depositionAY for eh ny deposition on nE nd pEsnqesD the growth experimenE tl onditions were extly the sme @oth sustrtes were in the retor hmer t the sme timeAF he expeted thikness of the zin oxide lyers n e determined from the urve shown in pigure RFU@D IPH • urveA in ghpter RF el pds were lso deposited on nE nd pEsnqes smples without nyD for reting referene smplesF le TFP gives the numer of evh yles nd the smple lels used in the textF le TFPX xumer of ny evh yles nd smple lels fter el pds deposition on nE nd pEsnqes smplesF he thikness of the el pds deposited y sputtering ws 600nm @note tht the thikness of the ny lyer deposited y evh inreses nonlinerly with the numer of yles up to TH ylesAF xme xumer of ny evh yF nEsnqes pEsnqes H elGnEsnqes elGpEsnqes PH elGny@PHyAGnEsnqes elGny@PHyAGpEsnqes PS elGny@PSyAGnEsnqes elGny@PSyAGpEsnqes QH elGny@QHyAGnEsnqes elGny@QHyAGpEsnqes RH elGny@RHyAGnEsnqes elGny@RHyAGpEsnqes SH elGny@SHyAGnEsnqes elGny@SHyAGpEsnqes he thikness of the el ontts ws THH nmF fefore evh proessD the snqes sustrtes were gitted in Rw rgl solution for S min to remove the ntive oxideD rinsed in deionized wter for QH sD nd then dried with rgon )ow efore immedite introdution into the evh retor @see setion IFIFPFR of ghpter IAF por ny evhD snqes sustrtes were heted up to IPH • gF por eh evh yleD diethylzin or n@g 2 r 5 A 2 @hinA ws used s metlli preursor @5sccm )ow during 5 secAD moist ir ws used s n oxidnt @IHH sm )ow during 10 secAD nd nitrogen ws used for purging etween the pulses @IHHH sm )ow during 45 secAF es shown in the hpters devoted to the ny growth on snqesD the thikness of the ny 130 Chapter 6. Electrical measurements lyer inreses nonlinerly with the numer of yles up to TH ylesF es for el deposition on re snqes surfeD snqes smples were ethed in rgl using the sme proedure s the one desried oveD then xi stenil ws refully stuk onto the surfeD el ws deposited through the stenil pertures nd t lst the stenil ws removedF xote tht rther long time lsts from the moment when rgl ething (nished until the moment when el deposition strted @the smples were in the open ir for long time nd snqes surfe ould e oxidised ginAD then one nnot exlude tht the ntive oxide formed on the snqes surfes efore el depositionF pigure TFV@A shows n exmple of n imge of el ontts on the snqes surfeD otined with n optil mirosope @ywAF flk dshed frmes on the yw imges show the stenil sizes of el ontts for eh lineF st n e seen tht the ontts do not hve stritly retngulr or squre shpeD the edges re slightly smoothed nd they protrude eyond the frme oundriesF es stted oveD this ws expeted euse gp in etween the stenil nd smple surfe leds to the shdow e'et @prt of the metl )ows eyond the oundries of the pertureD see (gF TFU@AF por tht resonD for some smples nd lowest distnes etween pds we ould see pds glued together into oneF henD of ourse one ould not mesure the eletril resistne etween these onttsF roweverD for most of the smples the ontts were well seprtedF 6.2.1.2 ZnO etching in HNO 3 acid efter el deposition on nyGsnqes smplesD ny lyer is present under el pds nd in etween el pds s shown in (gure TFW@A on the leftF he use of stenil for elGny ontts retion mkes di0ulties in reting ontts tht re not onneted y nyF he ny evh lyer is present etween the metl ontts when the stenil method is usedF he ny lyer present in etween the el pds n e dissolved in rxy 3 id provided tht the id onentrtion nd ething time re optimized @pigure TFW@AAF sf the id onentrtion is too high nd ething time too longD then it is possile to dissolve the THH nm of elF hereforeD we hose n id onentrtion nd ething time to otin ny ething speed of out severl nnometers per minuteF henD only the upper prt @severl nnometersA of the el pds is removed wheres the few nm of ny in etween the el pds in the lterl plne re fully ethedF por (nding the orret reipeD we ethed series of nyGi smplesD the thikness of the ny lyer efore ething ws out IH nm @SH yles of ny evhY the thikness is lultedD sed on qg vlue for ny on iAF e quntittive ontrol of ny lyer thikness efore nd fter id tretment ws rried out y mesuring the n nd i Ery )uoresene signls using inergyEdispersive Ery petrosopy @ihA inside nning iletron wirosope @iwAF fy ompring the intensities of the n v α pek integrted intensity to the totl intensity of the n v α nd i u α peks for di'erent smples it ws possile to monitor qulittively the hnge of ny thiknessF he energy of the iw eletron em ws set to Q keD llowing us to detet the n v α )uoresene pek of ny lyers not thiker pigure TFWX @A hemti representtion of the ething proedure of the ny lyer etween el ontts in rxy 3 id solutionF he ny lyer n e dissolved if the right id onentrtion nd ething time re hosenF @A hependene of the nG@nCiA )uoresene rtio @green irles onneted y the green lineA of the nyGi ethed smple in rxy 3 id solution upon the rxy 3 onentrtionF he ornge dshed line orresponds to the nG@nCiA )uoresene intensity rtio of one nyGi smpleD mesured efore id tretmentF he ething time ws 1 minF por n id onentrtion vlue of 3.5 × 10 -4 mol/L @lue dshed retngleAD the nG@nCiA )uoresene rtio vlue is out four times less thn for nonEethed nyGi smple @ornge dshed lineAF @A he dependene of the nG@nCiA )uE oresene rtio upon the ething timeD for rxy 3 onentrtion vlue equl to 3.5 × 10 -4 mol/LF thn QER nmF he ornge dshed line in pigF TFW@A shows the nG@nCiA )uoresene inE tensity rtio of nyGi smpleD mesured efore id tretmentF his nyGi smple ws ut into severl pieesD eh of these ws ethed y dipping it into n rxy 3 id solution for 1 minD the id onentrtion eing di'erent for one piee to notherF he green irles onneted y the green line in pigF TFW@A show the dependene of the nG@nCiA )uoresene rtio of the nyGi smples ethed in rxy 3 id solutionD upon the rxy 3 molr onentrtionF yne oserves tht for n id onentrtion vlue of 3.5 × 10 -4 mol/L @the point is loted in lue dshed squreAD the nG@nCiA )uoresene rtio vlue is out four times less thn for the nonEethed nyGi smple @ornge dshed lineAF his mens tht t this onE entrtion the ny lyer hs een notielyD ut not ompletely ethed during one minuteF his orresponds to ny ething rte of severl nnometers per minuteF por other series of the sme nyGi smplesD we studied the dependene of the nG@nCiA )uoresene rtio upon the ething timeD when rxy 3 ws 3.5 × 10 -4 mol/L @pigF TFW@AAF yne n see tht fter ething the nyGi smple in rxy 3 id for W minutesD the nG@nCiA )uoresene rtio for this smple is redued to HF his indites the thinning down of ny lyer t lest to thikness of QER nm or thinnerF husD for removing the ny lyer etween the el ontts of the elGnyGsnqes smplesD we hose the rxy 3 id onentrtion s 3.5×10 -4 mol/L nd the ething time ws 12 minF 6.2.1.3 Current-voltage characteristic for dierent lines of Al contacts e mesured the sE urves of elGny@PSyAGpEsnqes smple ethed in rxy 3 id solution with the four di'erent lines of el ontts @pigure TFIH@AAF ell eletriE l mesurements were performed on REproe mesurements rmmtsu sttion in ollortion with engineerEreserher vier wesot @esponsile for the eletril nd physil hrteriztion pltformD swiEvergD qrenoleAF he geometril prmeters of the ontts nd the distnes etween the ontts re shown in pigure TFVF pigure TFIHX @A e series of sE urves mesured etween el pds for the di'erent ontt lines @the geometril prmeters of the ontts nd the distnes etween the ontts re shown in pigure TFVAF @A otl resistne tot vlues etween pirs of ontts upon the distne etween the ontts for the four di'erent linesF he mesurements were rried out for the elGny@PSyAGpEsnqes smple ethed in rxy 3 id solutionF he sE urves mesured for di'erent pirs of ontts re liner in the voltge rnge EIDID showing tht the ontts re ohmiF pigure TFIH@A shows the the totl resistne tot etween pirs of ontts upon the distne etween the ontts for the di'erent lines for the sme smple @elGny@PSyAGpEsnqes ethed in rxy 3 id solutionAF he sE hrteristi for eh pir of ontts in pigF 6.2. Results and discussion 133 TFIH@A were (tted y stright linesD the inverse vlue of the slope determined the totl resistne tot for the orresponding pir of ontts in pigF TFIH@AF he totl resistne urves for ontt lines sEs were (tted y liner funtions @s disussed in setion TFIFPAF he oe0ient of determintion squred for this (ts re shown in tle TFQF le TFQX he oe0ient of determintion squred for liner funtions (ts of di'erent ontt lines tot @lA funtionsF gontt line Equre @gyhA line s HFWWUUQ line ss HFWVHTR line sss HFWWQRH line s HFRITWT pigure TFIH@A shows tht for line s nd sssD the points lie etter on the stright line @erson orreltion oe0ients re lose to IAD nd for the line s there is stter of vluesF hen the ontt size is smll @line sAD the ontt oundries fter deposition through the stenil re uneven nd the ontts hve di'erent shpe for lrge numer of smplesD nd this introdues dditionl dispersion into the eletril mesurementsF por ll susequent eletril mesurementsD line sss ws hosenD the ontt size is the lrgestD the ontts re of the sme shpe nd sizeD unlike other ontt linesD whih sometimes hve stuk together or uneven onttsF 6.2.1.4 TLM measurements for dierent thicknesses of ZnO layer e mesured the urrentEvoltge hrteristis @sE urvesA of the series of smples listed in le TFPD oth efore ething in rxy 3 id nd fter ethingF he line of el ontts sss @(gure TFVA ws used for mesurementsF sn (gure TFII we show exmples of suh sE hrteristis for three smplesX elGny@PHyAGnEsnqesD elGpEsnqesD elGny@PSyAGpEsnqesF ell other sE urves re presented in (gE ures fFVD fFWD nd fFIH in ppendix fF he sE urves of elGny@PHyAGnEsnqes smples re nonliner in the rnge EIDID with the resistne vlue rehing out IH kΩ @pigure TFII@AAD therefore they nnot e used for the spei( ontt resistivity determintion y pplying the vw model @setion TFIFPAF yn ontrryD sE urves for elGpEsnqes nd elGny@PSyAGpEsnqes smples @efore ething in idD pigsF TFII@A nd TFII@AA re liner in the rnge EIDI with muh lower urrent intensityF gompring the sE urves for oth smples it n e seen tht urrent intensity etween the sme ouples of el ontts is higherD nd onsequently the totl resistne dereses when thin ny lyer @out I nm thikA is inserted in etween the el ontt nd the snqes pEtype semiondutorF he vw method n e used for smples with ohmi onttsD thus we lulted the totl resistne dependene versus the distne etween the ontts only for pEtype snqes smplesF he sE urves mesured etween the el ontts of most nEsnqes smples were found to e pigure TFIIX eries of sE urves for three smplesX @A elGny@PHyAGnEsnqesD the sE urves re non liner @A elGpEsnqesD @A elGny@PSyAGpEsnqesF sn the se of elGpEsnqes @A nd elGny@PSyAGpEsnqes @AD the sE urves re liner nd the totl resistne dereses when thin ny lyer is inserted in etween the el ontt nd the snqes pEtype semiondutorF nonliner fter inserting the ny lyer in etween the el nd nEsnqes @see (gF fFV in ppendix fAF pigures TFIP@A nd TFIP@A show the totl resistne dependene upon the disE tne etween el ontts for di'erent pEsnqes smplesF he resistne ws meE sured etween el ontts of line sssD the ontts re onventionlly numered from I to VD s shown in pigure TFV@AF he totl resistne tot etween the pir of ontts ws lulted y tking the inverse of the slope of the sE urvesD whih were (tted y stright line in the voltge rnge from EI to I F he totl resistne ws mesured for the elGny@n yAGpEsnqes smplesD where n is the numer of evh yles used during ny evhY naH orresponds to the sitution with no ny lyer inserted in etween the el pd nd pEsnqesF pirstD the sE hrteristis were mesured for smples with ny in etween el onttsF henD these smples were ethed in rxy 3 id solution @rxy 3 onentrtion ws 3.5 × 10 -4 mol/LD ething time ws 12 minA to remove the ny in etween the el onttsD s desried in the setion TFPFIFPF pigure TFIP@A shows the totl resistne urves of the smples ethed in rxy 3 id solutionF foth (gures TFIP@A nd TFIP@A show the sme sE urves orresponding to elGpEsnqes smple without nyD it is nmed s 4H yles4D this smple ws not ethedF he experimentl totl resistne urves were (tted y liner funtionsF e oE e0ient of determintion squred lulted for tot @lA experimentl funtions for the elGpEsnqes smple ws HFTIF roweverD for instneD for tot @lA funtions mesured for elGny@PSyAGpEsnqes smples efore nd fter rxy 3 tretmentD squred ws lose to I @HFWU nd HFWWD respetivelyAF e n see tht tot @lA funtions for smples with ny@PSyA inserted in etween el nd pEsnqes hve smller spred of tot vlues nd this vlues re loser to the liner distriutionD in ontrst with tot @lA funtion for elGpEsnqes smpleF es shown in setion TFIFPFP for the wv methodD the est (t stright line tht est the tot vluesD interept the vExis t va2L x nd tot Exis t tot aP c F he L x nd R c vlues for the pigure TFIPX otl resistne dependene versus the distne etween ontts @pointsA mesured for di'erent pEsnqes smples @A efore nd @A fter rxy 3 tretmentD the resistne ws mesured etween el ontts of line sssD the ontts re onventionlly numered from I to VD s shown in pigure TFV@AF he urves were (tted y liner funtions @linesAF he L x nd R c vlues extrted from these urves re shown in le TFRF @A pei( ontt resistivity ρ c lulted y using expression TFSD knowing the experimentl L x nd R c vlues nd the width of the ontt @W = 400µmAF pEsnqes smples efore nd fter ething in rxy 3 id re given in le TFRF henD knowing the L x nd R c vlues nd the width of the el ontt @W = 400µmAD the spei( ontt resistivity ρ c n e lulted using expression TFSF he spei( ontt resistivity vlues for pEsnqes smples re shown in le TFR nd in pigure TFIP@AF st n e seen tht there is no derese in spei( ontt resistivity for most of the smples ethed in rxy 3 id for removement of the ny lyer onneting the el onttsF erhpsD due to the ft tht the ny lyer tht onnets the el pds is thin enoughD this lyer does not 'et the hnge in the ontt resistneF sn ontrstD for most of the smplesD we oserve slight inrese of spei( ontt resistivity vlue fter ething in rxy 3 idF ine we ethed in the rxy 3 id smE plesD whih were lredy mesured y four proes @the smples hs some footprints @holesA on the surfe of the metl onttsAD it is possile tht the ething smE ple proess introdues dditionl e'ets tht inrese the spei( ontt resistivity vlueF he smllest spei( ontt resistivity ρ c vlue ws hieved for the ontts of le TFRX he L x nd R c vlues for the pEsnqes smples efore nd fter ething in rxy 3 nd lulted spei( ontt resistivity ρ c F he length of the ontt is RHHµm @W = 400µmD line sss @pigF TFV@AAF retment mple v x @µmA c @ΩA ρ c @IH -3 Ω.cm es ws shown in the setion TFPFIFRD the smllest spei( ontt resistivity ρ c vlue ws hieved for the ontts of elGny@PSAGpEsnqes smple @with ny inserted in etween pEsnqes nd elAF e lso ttempted to eth this smple in id nd performed two experiments on nneling of this ethed smpleD to derese the spei( ontt resistivityF he nneling experiments were performed in olE lortion with eserh ingineer hilippe odriguez nd hFhF student wthieu fertrnd @vetiD tehnology reserh instituteD qrenole @prneAAF sn this setionD we ompre spei( ontt resistivity of elGpEsnqes smple @no ny lyerA with elGny@PSyAGpEsnqes smples treted di'erent wyF he sE hrteristis nd spei( ontt resistivity of elGpEsnqes smE ple nd elGny@PSyAGpEsnqes @efore nd fter ething in rxy 3 idA smples were lredy disussed in setion TFPFIFRF rereD we indite elGpEsnqes smple s S_noZnO nd elGny@PSyAGpEsnqes smple efore nd fter ething in rxy 3 id s S_b.HNO 3 nd S_a.HNO 3 respetively @see tle TFSAF o improve the dhesion of metl ontt to sustrte surfeD we nneled two elGny@PSAGpEsnqes smples previously ethed in 3.5 10 -4 w rxy 3 @IP min ething to remove ny in etween el onttsAF yne smple ws nneled t 250 • C for 1 min under nitrogen tmosphereD we indite this smple s S_250C @see tle TFSAF yther elGny@PSAGpEsnqes smple ws nneled t 350 • C for 1 min under nitrogen tmosphereD we onditionlly indite this smple s S_350CF 6.2. Results and discussion 137 henD the sE urves were mesured for nneled smples to determine spei( ontt resistivityF pigure TFIQ@A shows the experimentl totl resistne funtions tot upon the distne etween the onttsD tot vlues were otined from the sE urves (tted y stright line in the rnge from EI to I F pigure TFIQX otl resistne nd spei( ontt resistivity vlues for series of smples with pEsnqes sustrtesF @A otl resistne funtions tot of distne etween the ontts vD tot vlues were otined from the sE urves (tted y stright line in the rnge from EI to I F he lulted tot points were (tted y stright linesD the L x D R c nd lulted ρ c vlues re shown in le TFSF @A wesured spei( ontt resistivity ρ c vluesF he lulted tot points were (tted y stright linesD otined L x D R c vlues nd lulted ρ c vlues re given in le TFSF le TFSX he L x nd R c vlues for the elGpEsnqes nd di'erent elGny@PSyAGpE snqes smples exposed to hemil nd het tretmentY nd lulted spei( ontt resistivity ρ c F he lengths of the ontt re RHHµm the ontted deposited y stenil @W = 400µm forD line sss @pigF TFV@AA nd IHHµm for the ontted deposited using liftEo' method @pigF TFIS@AAF mpleGtretment xottion v x @µmA c @ΩA ρ c @IH -4 Ω.cm Frxy 3 smple @elGny@PSAGpEsnqesAF he nneling of the two smples did not hve ig impt on the spei( ontt resistivityD perhpsD y vrying the nneling prmetersD it is possile to redue the spei( ontt resistivityF

Conclusion

st n e oserved tht the spei( ontt resistivity ρ c dereses for some elGnyGpE snqes smples when ny lyer is inserted in etween el nd pEsnqesD ompre to ρ c vlue for elGpEsnqes smple without nyF he minimum of spei( ontt resistivity ws otined for the elGny@PSyAGpEsnqes smple efore the ething in rxy 3 idF he spei( ontt resistivity for elGny@PSyAGpEsnqes smple with ny lyer is lmost W times lower thn for the elGpEsnqes smple without ny lyerF he stenil ws used s quik method to hek the e'et of ny lyer on the qulittive hnge in ontt resistneF e more progressive method is photolithogE rphyD whih llows to rete the uniform smll ontts nd inrese the ury of mesurementsF 6.2.2 Photolithography method and results 6.2.2.1 Deposition of contacts using photolithography e used photolithogrphy liftEo' methodD unequl to the stenil methodD for metlE li ontts deposition on the snqes surfeF hotolithogrphy liftEo' method hs severl dvntges over the stenil methodF es disussed erlierD using stenE il method for metlGny ontts retionD resulting in forming the smples with ny etween metl onttsF sn ontrst to stenil methodD photolithogrphy liftEo' method llows forming metlGny ontts on the smples without ny etween onttsF repring n snqes smple for metl deposition using stenilD snqes smple is oxidized gin during stiking of the stenil on snqes surfeF sing photolithogrphy liftEo' methodD one n perform hemil ething of snqes smE ple with photoresist right efore metl deposition to rete metlGsnqes interfe without ntive snqes oxidesF he dvntge of using the photolithogrphy method insted of the stenil method is tht photolithogrphy llows the retion of smller identil ontts with n ury given y the ultrviolet wvelengthF hespite the ft tht the stenil method is fster nd heperD it lerly loses to photolithogrphy in ury nd does not llow reting so smll ojets s photolithogrphy llowsF he whole liftEo' proess ws rried out in ollortion with eserh ingineer hilippe oE driguez nd hFhF student wthieu fertrnd @vetiD tehnology reserh instituteD qrenole @prneAAF wetl ontts were rried out in ollortion with engineer ghristelle qomez @pstrem ehnologil ltform eD qrenole @prneAAF e shemti illustrtion of liftEo' method is shown in (gure TFIRF pigure TFIRX hotolithogrphy liftEo' proess for the retion of metl ontts with ny lyer inserted in etween the metl nd the smple surfeF @IA snqes sustrte prepred for photoresist depositionF @PA e IHHH nm thik photoresist on the snqes surfeX photoresist is deposited y spin otingD driedD irrdited through photomsk in the ultrviolet rnge to rete windows on photoresist whih n e diluted in the ethntD nd then photoresist ws dried ginF @QA snqes ontt res nd the rest of surfe whih is proteted y the photoresist @the smple is pled in the ethnt nd photoresist is ethed only in irrdited resAF @RA ny lyer is deposited in photoresistGsnqes y evh @the numer of evh yles is PSD it orresponds to the IEP nm thik ny lyerAF @SA PHH nm thik lyer of metl is deposited on the entire surfe of the smple y sputteringF @TA he liftEo' proedureX the smple is pled in etone for S minutesD to fll o' entire photoresist with metlGny lyers on it from the smple y dissolving the photoresist in etone nd leve only metlGnyGsnqes divided regionsF snqes sustrte @IA underwent stndrd photolithogrphy steps s desried in the followingF pirstD IHHH nm thik photoresist @S T M positive h photoreE sistA is deposited on the snqes sustrteD then the photoresist is driedD irrdited through photomsk with ultrviolet light @merury lmpD wvelength is PRH nmA using wtfR wsk elignerD nd then photoresist is dried gin @PAF he smple is pled in the ethnt nd the photoresist is ethed only in irrdited resF pinllyD snqes ontt res re formedD the rest of the snqes surfe sty proteted y the photoresist @QAF henD one deposits metl lyer on the photoresist nd the open regions of the snqes surfeD to rete metlGsnqes juntion @fter step QD we go diretly to step SAF o rete metlGny ontts on snqes surfeD we deposited (rst ny lyer on the photoresistGsnqes smples @RA y evhF efter the evh proessD thin ny lyer overs the photoresist surfe nd the snqes surfe in ontt res @RAF henD PHH nm thik lyer of metl @we used el or iA is deposited on the entire surfe of the smple @SA y sputtering using er plsm with hg voltge in hysil por heposition @hhA gIHH T M hmerF et (E nl stepD the liftEo' proedure is rried outX the smple is pled in etone for S minutes for dissolving the photoresistD then the entire photoresist with metlGny 140 Chapter 6. Electrical measurements lyers on top of it is lift o' from the smple surfeD leving metlGnyGsnqes pds on the surfeF es resultD the snqes smple ontins metlGnyGsnqes divided regions @TAD whih n e used s ontts to mesure eletril resistneF he geometri on(gurtion of metl ontts repets the pttern of the phoE tomskF pigure TFIS@A shows the plnned geometri prmeters of ontts oE tined y photolithogrphyF pigure TFISX @A lnned geometri prmeters of ontts otined y photolithogE rphyF even 100µm × 100µm squre ontts re loted on one stright lineD we onditionlly numered them from one to sevenF he distne etween neighoring ontts inresesX 20µm etween the (rst nd seond ontts @20µm for 12AD 40µm for 23D 60µm for 34D 80µm for 45D 120µm for 56D 150µm for 67F @A en optil mirosope @ywA imge of el ontts otined y photolithogrphy liftEo' methodF even 100µm × 100µm squre ontts re loted on one stright lineD we numE er them from one to sevenF he distne etween neighoring ontts inresesX 20µm etween the (rst nd seond ontts @20µm for 12AD 40µm for 23D 60µm for 34D 80µm for 45D 120µm for 56D 150µm for 67F pigure TFIS@A shows n optil mirosope @ywA imge of metl onttsD it is ler tht the dimensions of the ontts oinide with the plnned dimensionsF he edges of the ontts re evenD nd the ontts re well seprted from eh otherF e mde ontts on T smples using the liftEo' photolithogrphi methodF e frited three smples with metl ontts on snqes without ny inserted etween metl nd snqesX elGnEsnqesD elGpEsnqesD nd iGpEsnqesY three smples with ny inserted etween metl nd snqesX elGnyGnEsnqesD elGnyGpE snqesD nd iGnyGpEsnqesF ny ws deposited on photoresistGsnqes suE strtes y tomi lyer deposition @evhAF fefore evh proessD the photoresistGsnqes sustrtes were gitted in Iw rgl solution for Q min to remove the ntive oxide on open snqes surfeD rised in deionized wter for QH sD nd then dried with rgon efore immedite introdution into the evh retorF por the ny evhD photoreE sistGsnqes sustrtes were heted up to IPH • gF por every evh yleD diethylzin or n@g 2 r 5 A 2 @hinA ws used s metlli preursor @5sccm )ow during 5 secAD r 2 y ws used s n oxidnt @Q sm )ow during 40 secAD nd nitrogen ws used s the purging gs etween the pulses @IHHH sm )ow during 45 secAF he numer of evh yles ws PSD this ensure the full overge of the snqes surfe with I nm thik ny lyerF ell three sustrtes were pled in retor hmer t the sme timeF 6.2.2.2 TLM measurements for samples obtained by photolithographic method o determine spei( ontt resistivity of T smples prepred using photolithogrE phyD we used vh methodF e hve to note tht the distnes etween the metlli pdsD otined for these smplesD re in the rnge from PH µm to ISH µmD in ontrst to the distnes etween metlli pds otined y using stenil @the distnes re in the rnge from SH µm to SHH µmAF por shorter distnes etween metl pdsD the in)uene of the sustrte resistne deresesD nd the in)uene of the ontt resistne inreses @see iqF TFUAD whih n 'et the sE hrteristiF pigure TFIT shows the sE hrteristis mesured etween the neighoring onE tts of six smples @three smples without ny in etween the metl nd snqes nd three smples with ny in etween metl nd snqesAD y using the sme experimentl onditions s desried ove in etion TFPFIFIF pigure TFITX sE hrteristis mesured etween the neighoring ontts of six snqes smples without ny inserted in etween metl nd snqesX @A elGnE snqesD @A elGpEsnqesD nd @A iGpEsnqes nd three smples with ny inserted in etween metl nd snqesX @dA elGnyGnEsnqesD @eA elGnyGpE snqesD nd @fA iGnyGpEsnqesF ell the smples were otined y liftEo' phoE tolithogrphy proessF es n e seen from pigF TFIT@AD for elGnEsnqes smpleD the sE urves re liner like for ohmi onttsD instedD fter the insertion of ny lyer @elGnyGnE snqes smpleAD the sE hrteristis eome nonliner nd the urrent is muh smller for given voltge @pigF TFIT@dAAF yn the ontrryD for elGpEsnqes smple the urrentEvoltge hrteristis mesured etween el ontts re nonliner @pigF TFIT@AAD ut with ny insertion@elGnyGpEsnqes smpleAD the totl resistne dereses nd the urrent intensity is higher @pigF TFIT@eAAF hen i is used s ontt metlD one n oserve tht the sE urves for iGpEsnqes smple re liner @pigF TFIT@AA nd tht the urrent dereses with the introdution of ny lyer @iGnyGpEsnqes smple @pigF TFIT@fAAF erhps i is more suitle metl for mking ontts on snqesD in view of the higher i work funtion @Φ T i = 4.3eV A thn el work funtion @Φ Al = 4.16eV AD whih is loser to i i InGaAs = 4.87eV F hen linerD the sE urve ws (tted y stright line nd the totl resistne ws lulted y tking the inverse vlue of the slopeF pigure TFIU shows the vlues of the totl resistne s funtion of the distne etween the ontts @the distnes etween the ontts re shown in pigure TFIS@AA for elGnEsnqesD elGny@PSyAGpEsnqesD nd iGpEsnqes smplesF e ssoite the nonlinerity of some of the sE urves mesured for photolithogrphi smplesD ompre to the stenil smplesD with the ft tht the distne etween ontts in is smller in the (rst se nd the resistne indued y the sustrte is reduedF pigure TFIUX he vlue of the totl resistne s funtion of the distne etween the ontts @the distnes etween the ontts re shown in pigure TFIS@AA for elGnEsnqesD elGny@PSyAGpEsnqesD nd iGpEsnqes smplesF he tot @symE olsA vlues were (tted y liner funtions @stright linesAF he orresponding L t nd R c vlues re given in le TFT for the three smplesF he tot vlues were (tted y stright line for eh smpleF he L x nd R c vlues re shown in le TFTD for eh smpleF le TFT gives lso the experimentl spei( ontt resistivity ρ c vluesD luE lted y using expression TFSD nd metl pd width equl to 100µm @W = 100µmD see pigF TFIS@AAF le TFTX he L x nd R c vlues for elGnEsnqesD elGny@PSyAGpEsnqesD nd iGpEsnqes smples nd lulted spei( ontt resistivity ρ c F he length of the ontt is IHHµm @W = 100µm @pigF TFIS@AAF mple v x @µmA c @ΩA ρ c @IH -4 Ω.cm 2 A elGnEsnqes QUFQ SQFV PHFI elGny@PSy Λ AGpEsnqes WQFW QHFI PVFQ iGpEsnqes QRFQ IHFH QFR

Conclusion

e mesured the sE urves nd spei( ontt resistivity for groups of metlGnyGsnqes smples with di'erent thiknesses of nyF por smples with ny introdued in eE tween el nd nEtype snqesD the sE urves demonstrted nonliner ehviorD s in the se of the hottky rrierD in ontrst to the sE urves mesured for the elGnE snqes smple without ny @ohmi onttsAF sn ontrst to the nEtype snqes smplesD in the se of ny introdued in etween el nd pEtype snqesD the sE urves eome linerD in ontrst to the sE urves mesured for the elGpEsnqes smple without nyF he introdution of ny in etween el nd pEsnqes lso redues the spei( ontt resistivityF por instneD the spei( ontt resistivity vlue ws lmost W times deresed for elGny@PSyAGpEsnqes smple @with ny inserted in etween el nd snqesAD ompred to n elGpEsnqes smple without nyAF he ething nd nneling of this smple did not led to n dditionl derese of spei( ontt resistivityF por omprisonD i ws used s metl for iGpEsnqes ontts retionF he sE urves mesured for iGpEsnqes ontts re liner @iGpEsnqes ontts re ohmiAF erhps the hoie of nother metl for onttD in perspetivesD n llow performing lower spei( ontt resistivity vluesF

Conclusion and perspectives

sn this workD we foused on the study of the initil stges of ny evh on @IHHAsnE qesF por investigting the ny initil growth stgesD we used therml evh retor wyyx tht llows monitoring growth in situ y optil nd synhrotron methodsF huring my hFhFD the wyyx retor ws retro(ttedF e instlled ypss gs lines whih llow stilizing the )ows nd pressures of preursors nd purge gses efore their injetion into the retor hmerF e lso estlished the use of metl preursor evportor insted of ulerD whih llowed us to more urtely ontrol the mount of injeted preursor into the retor hmerF sn ddition to the existing x 2 y preursor injetion systemD we instlled wter evportorD llowing to use pure gs wter s n oxidnt for ny evhF ell these hnges mde it possile to otin stle nd reproduile evh proessF e further upgrde would e to instll wter mss )ow ontroller @wpgA inE sted of the needle vlve urrently used for n esier nd preise ontrol of the wter )ow during oxidnt pulseF sn the ner future it is plnned to instll residul gs nlyzer @qeA for hemil nlysis of the yprodut during evhF st is lso plnned to use optil methods @ellipsometry nd wultiem yptil tress ensor @wyAAD ville in the lortory to monitor growth in situF egrding synE hrotron methodD n e'ort should e put on the retro(t of the retor for llowing to perform qse experiment @notly y instlling ldes nd em stops inside nd outside the retor for utting down the di'use stteringAF fy using synhrotron tehniques during ny evhD we showed tht the ny growth on rgl lened @IHHAsnqes surfe psses through trnsient regime whih is omprised of two stges prior to the stedy liner growthF huring the initil stge of growthD ny lyerD out I nm thikD is formedF his lyer formtion n lst severl evh ylesY in prtiulrD it depends on the wter )ow vlueF sn the mnusriptD this timeElpse is lled inution time or dely timeF his ny lyer is hrterized y shortErngeEordered tomi strutureD with n emryoni ny wurtzite strutureF henD with inresing the equivlent thikness of ny lyerD Qh islnding @rougheningA egins @sustrteEinhiited growth of type PAD longErnge ordered wurtzite struture developsD (nlly the growth enters into the third nd lst stgeD tht is stedy liner growthF huring stge P of the trnsient regimeD inE plne ny wurtzite Ery di'rtion peks pper when the qg funtion rehes mximumD iFeF little efore stedy growth eginsD on(rming the pperne of long rnge ordered strutureF hi'erent ny lyer textures re oservedD depending on the sustrte tempertureF righ temperture fvors the texturtionF es fr s we knowD no one hs ever reported on mterils frited during this initil inution periodF e lso developed geometri model of hemispheroid islnd Conclusion and perspectives evh growthD whih llows simulting the qg urvesD whih re hrteristi of sustrteEinhiited growth of type PF sn our modelD we ssume tht hemispheril islnds re loted in the enters of squre lttieF e further improvement of the model would e to simulte growth onditions tht re possily loser to the experimentl growth onditionsD iFeF the growth of rndomly loted islnds with rnge of size ndGor spet rtio distriutionsF e lso demonstrted derese of the ohmi ontt resistne for the elGnyGpE snqes smple in omprison with the elGpEsnqes smpleD iFeF without the ulE trthin tunnel ny lyerF yne the wyyx retor nd growth proess were redyD we did not hve enough time for more systemti sreening of the metl nd ny lyer thikness for eletril mesurementsF e more pproprite metl nd thikness vlue ould further derese the ontt resistne either with pE or nEsnqesF pollowing the trk of pioneering studiesD my work demonstrtesD one ginD the power of in situ synhrotron methods for understnding the tomisti proesses tkE ing ple during the initil stges of gh growthD more spei(lly evhF elthough we fous on the erliest stges of ny depositionD our results nd the tehniques we employ re rodly pplile to welth of other oxideGsemiondutor systemsF Summary his work fouses on the study of the initil stges of ny tomi lyer deposiE tion @evhA on tomilly )t @IHHA sn 0.57 q 0.43 es surfeD notly y using in situ synhrotron tehniquesF hue to high eletron moilityD sssE snqes semionduE tor hs een reognized s promising mteril to reple ilion hnnel in the metlEoxideEsemiondutorE(eldEe'et trnsistors @wypiAF ltrthin ny lyer on snqes n e used s pssivtion lyer t the interfe with the gte trnsisE tor dieletriD s well s tunneling lyer inserted in etween metlGsnqes ontt to derese the hottky rrier height nd the ontt resistneF sn the reent yersD evh tehnique sed on selfElimiting surfe hemil retions hs reeived worldEwide ttention for mnufturing highly onforml nd homogeneous thin (lms with suEnnometer thikness ontrol t low tempertures omptile with industry spei(tionsF roweverD the growth ehvior strongly di'ers depending on the sustrte surfesF hus for the retion of few monolyers thik (lmsD the study of evh in the initil stges of growth is of prtiulr interest for improving the understnding of the growth mehnismsF por tht purposeD we hve developed nd upgrded therml evh retor @wyyxX wyghGevh growth of yxide xnostruturesA dedited to monitor the growth of mterils y in situ hrteriztion tehniquesF he wyyx retor n e moved to synhrotron enters for monitoring mteril growth in situ y using Ery sed tehniquesD notly Ery )uoreseneD Ery sorptionD D nd grzing inidene di'rtionF elsoD optil in situ tehniques n e used in the lorE toryF sn this workD we show the results of experiments otined t two synhrotron emlinesD iFeF ss @yvisvD intEeuin @prneAA nd shQ @ipD qrenole @prneAAF e show tht ny growth in the initil stges is inhiited y the @IHHA snqes sustrteD leding to trnsient regime prior to the stedy evh is hievedF e report detiled investigtion of this trnsient regime nd (nd tht n ultrEthin @∼ 1EnmEthikA Ph lyer is indeed frited ut with growth rte so low tht one my elieve tht nothing hs een deposited on the surfeF e identify the struturl nd hemil properties of tht ultrEthin lyerF ynly fterwrd does the sustrte inhiited of type P growth mode eginsX s the yle numer inresesD the growth per yle @qgA inresesD then rehes mximum nd level down to onstnt vlue @stedy growthAF por etter understnding of the Qh growth mode y reproduing the experimentl growth per yle urves we hve developed geometri model tht shemtizes the growth of hemispheroid islnds y evhF e show tht this model llows otining quntittive growth prmetersF hen wter is used s retntD we showed tht y hnging the wter )ow during the evh proessD it is possile to ontrol the time dely @or yle numerA Résumé ge trvil porte sur l9étude des étpes initiles du dépôt de ouhes tomiques de ny @evhA sur une surfe @IHHA de sn 0,57 q 0,43 esD pr l9utilistion de tehniques de rtéristion in situ @ryonnement synhrotronAF in rison de l grnde moilE ité des életronsD le semiEonduteur sssE snqes est un mtériu potentiel pour rempler le nl de iliium dns les trnsistors à e'et de hmp @wypiAF e(n de diminuer l huteur de l rrière hottky et l résistne de onttD une ouhe ultrEmine @tunnelA de ny peut être insérée entre le métl et le semionE duteur snqesF eu ours de es dernières nnéesD l tehnique evhD omptile ve les spéi(tions de l9industrie et sée sur des rétions himiques de surE fe utoElimitntesD est utilisée pour l frition de (lms mines onformes et homogènes ve un ontrôle suEnnométrique de l9épisseurF gependntD le omE portement u ours de l roissne di'ère fortement en fontion de l surfe du sustrtF einsiD l9étude des premières étpes evh est prtiulièrement intéressnte (n d9méliorer l ompréhension des ménismes de roissne en vue de l rétion de (lms ultrEminesF our e fireD nous vons développé et mis à niveu un réteur thermique evh @wyyxA dédiéF sl peut être instllé sur des lignes de lumière synhrotron (n d9étudier l roissne des mtériux in situ ve des tehniques telles que l )uE oresene D l9sorption D l spetrosopie des ryons insi que l di'rtion en inidene rsnteF he plusD des tehniques optiques de rtéristion in situ peuvent être utilisées en lortoire ou ouplées en milieu synhrotronF ves expériE enes u synhrotron ont été rélisées sur les lignes de lumière ss @yvisvD intEeuin @prneAA et shQ @ipD qrenole @prneAAF xous montrons que dns s phse initileD l roissne evh de ny est inhiée pr le sustrt @IHHA snqesD e qui onduit à un régime trnsitoire vnt le régime de roissne evh stleF v première phse du régime trnsitoire onduit à l forE mtion d9une ouhe d9oxyde de inD ultrEmine @∼ 1 nm d9épisseurAD friquée ve un tux de roissne très fileF v9sorption et l di'usion en inidene rsnte montrent qu9à e stde le mtériu ny est désordonné @non ristlliséA et présente un ordre à ourte distne rtérisé pr une struture wurtzite emryE onnireF insuiteD le régime trnsitoire entre dns une deuxième phse @roissne QhAD le tux de roissne pr yle @qgA ugmenteD tteint un mximum puis diminue jusqu9à une vleur onstnte @roissne evh stleAF e(n de mieux omE prendre le mode de roissne Qh nous vons développé un modèle géométrique qui shémtise l roissne d9¢hémisphériques pr evhF ge modèle permet d9otenir des prmètres quntittifs de roissneF in modi(nt le déit d9eu @r 2 yA utilisée omme rétif pendnt le proessus evhD il est possile de ontrôler le déli @ou le nomre de ylesA vnt le déut de Résumé l roissne QhF get e'et est très prolement lié à l vrition de l densité des groupes hydroxyle à l surfe de l9snqesF r illeursD nous vons rtérisé l roissne evh de ny pour di'érentes tempértures du sustrt snqes @dns et hors fenêtre evhAF ves rtes de di'usion des rélisées en ours de dépôtD monE trent l9pprition d9une phse ristllisée à longue distne en lien ve le démrrge de l roissne QhF à tempérture élevéeD hors de l fenêtre evhD nous oservons une texturtion de l ouhe ny lorsque son épisseur ugmenteF euune reltion d9épitxie n9est oservéeF in(nD nous rendons ompte de l9utilistion de ouhes ny ultrmines sur snqes pour les ontts életriquesF v résistne de ontt des éhntillons de métlGnyGsnqes été mesurée à l9ide de l méthode rnsfert vength wethod @vwAF xous montrons que l résistivité de ontt spéi(que des tmpons elGpE snqes est réduite pr l9insertion d9une ouhe tunnel ny entre l9el et l9snqes dopé pF

Summary

This work focuses on the study of the initial stages of ZnO atomic layer deposition (ALD) on atomically flat (100) In 0.57 Ga 0.43 As surface, notably by using in situ synchrotron techniques. Due to high electron mobility, III-V InGaAs semiconductor has been recognized as a promising material to replace Silicon channel in the metaloxide-semiconductor-field-effect transistors (MOSFET). Ultrathin ZnO layer on InGaAs can be used as a passivation layer at the interface with the gate transistor dielectric, as well as tunneling layer inserted in between metal/InGaAs contact to decrease the Schottky barrier height and the contact resistance. In the recent years, ALD technique based on self-limiting surface chemical reactions has received world-wide attention for manufacturing highly conformal and homogeneous thin films with sub-nanometer thickness control at low temperatures compatible with industry specifications. However, the growth behavior strongly differs depending on the substrate surfaces. Thus for the creation of few monolayers thick films, the study of ALD in the initial stages of growth is of particular interest for improving the understanding of the growth mechanisms.

For that purpose, we have developed and upgraded a thermal ALD reactor (MOON:MOCVD/ALD growth of Oxide Nanostructures) dedicated to monitor the growth of materials by in situ characterization techniques. The MOON reactor can be moved to synchrotron centers for monitoring material growth in situ by using X-ray based techniques, notably X-ray fluorescence, X-ray absorption, XRR, and grazing incidence diffraction. Also, optical in situ techniques can be used in the laboratory. In this work, we show the results of experiments obtained at two synchrotron beamlines, i.e. SIRIUS (SOLEIL, Saint-Aubin (France)) and ID3 (ESRF, Grenoble (France)).

We show that ZnO growth in the initial stages is inhibited by the (100) InGaAs substrate, leading to a transient regime prior to the steady ALD is achieved. We report a detailed investigation of this transient regime and find that an ultra-thin (~1-nm-thick) 2D layer is indeed fabricated but with a growth rate so low that one may believe that nothing has been deposited on the surface. We identify the structural and chemical properties of that ultra-thin layer. Only afterward does the substrate inhibited of type 2 growth mode begins: as the cycle number increases, the growth per cycle (GPC) increases, then reaches a maximum and level down to a constant value (steady growth). For a better understanding of the 3D growth mode by reproducing the experimental growth per cycle curves we have developed a geometric model that schematizes the growth of hemispheroid islands by ALD. We show that this model allows obtaining quantitative growth parameters.

When water is used as a reactant, we showed that by changing the water flow during the ALD process, it is possible to control the time delay (or cycle number) prior to 3D growth begins. It is very likely that the water flow controls the density of hydroxyl groups on the InGaAs surface. We also demonstrated ZnO ALD for different InGaAs substrate temperatures. By combining in situ X-ray absorption and grazing incidence scattering techniques, we identified a short-range-order atomic structure of the ZnO material, with an embryonic ZnO wurtzite, prior to 3D growth, then a long-range-order structure is detected both by X-ray absorption and X-ray diffraction, together with the appearance of a microstructure. At higher growth temperature, outside of the ALD window, we observed the well-known ZnO texturing when the layer thickness increases.

At last, we report on the use of ultrathin ZnO layers on InGaAs in the electrical contact structure. The contact resistance of metal/ZnO/InGaAs samples was measured using Transfer Length Method (TLM). We show that specific contact resistivity of Al/p-InGaAs pads is reduced by inserting a ZnO tunnel layer in between Al and p-doped InGaAs.

  . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54 3.2 Hemispheroidal islands model . . . . . . . . . . . . . . . . . . 56 3.3 Simulation algorithm using hemispheroidal islands . . . . . 59 3.4 Analysis of GPC functions using the model of hemispherical islands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62 3.4.1 Radius of curvature is constant . . . . . . . . . . . . . . . . . 63 3.4.2 n c is constant . . . . . . . . . . . . . . . . . . . . . . . . . . . 65 3.4.3 ∆ r is constant . . . . . . . . . . . . . . . . . . . . . . . . . . 66 3.4.4 Example of t with hemispherical-island model . . . . . . . . 66 3.5 Initial surface RMS eect on GPC shape . . . . . . . . . . . 68 3.6 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73 List of main characters b: the nerest distne etween two nulei r 0 : the se rdius of initil hemispheroidl islnd nuleus 54 Chapter 3. Island growth modeling h 0 : the height of initil hemispheroidl islnd nuleus

  (lms xilsen PHHUD xilsen PHHUdF xilsen et al. xilsen PHHU showed tht simultion of the growth of morphous lyers y evh n e rried out y pling geometril ojets rndomly or in n orderly mnnerF por instneD the geometril ojets n e hemispheres or hemispheroidsD pyrmidsD uesD prismsD or other Qh geometril ojetsF pigure QFP shows n exmple of simultion xilsen PHHU of the growth of hemispheril islnds with given surfe density nd rndomly positioned on the surfeF he pigure QFPX isuliztion of growth of hemispheril islnds with given density pled t rndom on the surfe xilsen PHHUF simultion spe orresponds to lttie omprising ellsF genters of the hemispherE il ojets re rndomly positioned in the lttie ellsF por every evh yleD eh ojet size is inremented y one growth lyerF he geometril simultion of islnd 56 Chapter 3. Island growth modeling

  shows lE ulted vlues of ∆ GP C nd GP C nc versus n c for the (xed R = (2/π)•10 3 cy 3 .nm -1 F snside gry retngles in (gure QFV@A re shown ∆GP C nd GP C vlues for the sme n c vlues s those of urves shown in (gure QFUF pollowing the sme wy of pigure QFVX glulted vlues of ∆ GP C @red losed tringlesA nd GP C nc @lue losed irlesA s funtions of n c @A nd ∆r @A for the (xed R = (2/π) • 10 3 cy 3 .nm -1 F he n c nd ∆r vlues of the dt points inside the gry retngles re the sme s those of the urves shown in (gure QFUF lultionD we otin ∆ GP C nd GP C nc s funtions of ∆rX

66

  Chapter 3. Island growth modeling 3.4.3 ∆ r is constant e onsider the lst se of reltions etween RD n c D nd ∆r when ∆r is onstntF henD R is squre funtion of n c with onstnt oe0ient (1/π∆r)X R(n c ) = 1 π∆r × n 2 c , @QFPWA nd b is liner funtion of n c with onstnt oe0ient 2∆rX b(n c ) = 2∆r × n c . @QFQHA pigure QFIH shows n exmple of series of qg urves for di'erent n c = 17, 18, .. , 23 when ∆r is (xedF fy inresing n c for (xed ∆rD we inrese @ording to eqution pigure QFIHX eries of qg urves simultion when the ∆h = ∆r is (xedF por ∆r = 0.2nmD the numer of yles when the islnd olesene strts is vried @n c = 17, 18, .., 23AF hen n c inreses linerly @gry dotted line is shifted to higher yle numersAD the rdius of urvture of qg funtion in hse s inreses s funtion of n 2 c F he distne etween the enters of islnds b inreses linerly with n c F he mximum of qg is onstnt for di'erent n c when ∆r is (xedF QFQHAF snresing b results in the inresing of RF his is euse for the sme islnd size nd the sme ∆r ut for lrger bD the verge thikness nd qg re lowerF yne n notie tht the GP C max D GP C nc D nd ∆ GP C re not hnged when ∆r is (xed due to the ft tht GP C nc nd ∆ GP C re lwys onstnt for di'erent n c when ∆r is onstntF he onstnt vlues of GP C nc D nd ∆ GP C n e lulted using eqution QFPSF

  . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94 5.2 Oxidant ow variation . . . . . . . . . . . . . . . . . . . . . . 95 5.2.1 Analysis of the reected beam intensity oscillations . . . . . . 95 5.2.2 Monitoring ALD in situ during the growth . . . . . . . . . . 98 5.2.3 Analysis of the surface and uniformity of the samples . . . . 102 5.2.4 Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103 5.3 Substrate temperature variation . . . . . . . . . . . . . . . . 104 94 Chapter 5. Synchrotron in situ studies, part II (ID3-ESRF) 5.3.1 Monitoring ALD in situ during the growth . . . . . . . . . . 105 5.3.2 Live measurements during ALD at 240 • C . . . . . . . . . . . 111 5.3.3 Analysis of the surface and uniformity of the samples . . . . 113 5.3.4 Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115 5.4 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117

  projetion of the wvevetor trnsfer on the zExis perpendiulr to the smple surfeY nd | k Iz | = | k Rz | = n • sin(A i )/λ re moduli of the inident nd re)eted wvevetor projetions on the zExisF hen we n rewrite equtions SFP for oserving onstrutive nd destrutive interferene sX

110Chapter 5 .

 5 Synchrotron in situ studies, part II (ID3-ESRF) le SFRX ny urtzite interplnr distnes d hkl @aQFPRWVPÅD aSFPHTTIÅAD stndrd reltive intensities of ny powder di'rtion peksD nd willer indies (h, k, l)F d EA wesured intensities s funtion of the interplnr distne d otined y integrting the di'rtion rings over the ngle ϕ nd using the eqution SFVD @dEfA Qh plots of the Intensity(d, n) versus interplnr distnes d mesured fter di'erent numer of evh ylesD nD for the three smples with grown t di'erent sustrte temperturesX @D dA IPH • gD ITH • g @D eAD nd @D fA PHH • gF

Contents 6 . 1

 61 Introduction and methods . . . . . . . . . . . . . . . . . . . . 119 6.1.1 Ohmic and Shottky contacts and Fermi level pinning . . . . . 120 6.1.2 TLM measurements . . . . . . . . . . . . . . . . . . . . . . . 124 6.2 Results and discussion . . . . . . . . . . . . . . . . . . . . . . 126 6.2.1 Stencil method and results . . . . . . . . . . . . . . . . . . . 126 6.2.2 Photolithography method and results . . . . . . . . . . . . . 138 6.2.3 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143

  Contents 2.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 2.2 Available in situ characterization techniques . . . . . . . . . 26 2.3 ALD implementation with the MOON reactor . . . . . . . . 29 Chapter 2. MOON: An ALD/CVD reactor for in situ studies 2.3.2 DEZn injection . . . . . . . . . . . . . . . . . . . . . . . . . . 33 2.3.3 Ar, N 2 , and N 2 O gas injection, pumping . . . . . . . . . . . . 41 2.3.4 Substrate heating system . . . . . . . . . . . . . . . . . . . . 43 2.4 Atomic layer deposition process . . . . . . . . . . . . . . . . . 46 2.4.1 ZnO atomic layer deposition process when N 2 O is used as an oxidant (g. 2.18) . . . . . . . . . . . . . . . . . . . . . . . . 47 2.4.2 ZnO atomic layer deposition process when water is used as an oxidant (g. 2.19) . . . . . . . . . . . . . . . . . . . . . . . . 48 2.5 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

  In situ synchrotron X-ray measurements . . . . . . . . . . . . 77 4.2.4 Ex situ measurements . . . . . . . . . . . . . . . . . . . . . . 78 4.3 Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78 4.3.1 XRF during growth . . . . . . . . . . . . . . . . . . . . . . . 78 4.3.2 Atomic force microscopy . . . . . . . . . . . . . . . . . . . . . 80 4.3.3 Film mean thickness and growth rate . . . . . . . . . . . . . 82 4.3.4 Fluorescence X-ray absorption near edge structure . . . . . . 84

Contents 4.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76 4.2 Experimental Section . . . . . . . . . . . . . . . . . . . . . . . 76 4.2.1 Substrate preparation . . . . . . . . . . . . . . . . . . . . . . 76 4.2.2 ALD reactor and parameters of deposition . . . . . . . . . . . 76 4.2.3

  PSAGpEsnqes smpleF e performed nneling experiment of this smpleD lredy ethed in id rxy 3 to inrese the dhesion of the metl ontt to the smple surfeD nd hek how this 'ets the hnge in spei( ontt resistivityF 6.2.1.5 The eect of dierent treatments of Al/ZnO(25cy)/p-InGaAs sample

					2 A
		elGpEsnqes	ITTFU	IUFH	IIFR
		elGny@PHyAGpEsnqes	PHPFW	IWFR	ISFU
	xot ethed	elGny@PSyAGpEsnqes elGny@QHyAGpEsnqes	SQFQ !	TFH !	IFQ !
		elGny@RHyAGpEsnqes	IUUFU	IVFT	IQFP
		elGny@SHyAGpEsnqes	IUPFU	IVFP	IPFT
		elGny@PHyAGpEsnqes	QITFH	PSFQ	QPFH
		elGny@PSyAGpEsnqes	IPUFH	IIFP	SFU
	ithed	elGny@QHyAGpEsnqes	IQTFQ	ISFU	VFT
		elGny@RHyAGpEsnqes	VRFU	IQFI	RFR
		elGny@SHyAGpEsnqes	QTRFS	PHFU	QHFP
	elGny@

  n see tht the spei( ontt resistivity ρ c vlues re lower for the nonyD Frxy 3 D Frxy 3 D PSHgD nd photF smples with ny lyer ompre to the elGpEsnqes smple without nyF he minimum ρ c vlue ws hieved for

	138	Chapter 6. Electrical measurements
					2 A
	elGpEsnqes without ny	S_noZnO	ITTFU	IUFI	IIQFT
	efore rxy 3 ethF	S_b.HNO 3	SQFQ	TFH	IPFW
	fter rxy 3 ethF	S_a.HNO 3 IPUFH	IIFP	SUFI
	rxy 3 ethFD nnF t PSH • g	S_250C	WIFR	VFU	QIFT
	rxy 3 ethFD nnF t QSH • g	S_350C	IRSFP	PUFP	ISVFI
	pigure TFIQ@A shows the mesured spei( ontt resistivity vlues ρ c for smE
	ples nonyD Frxy 3 D Frxy 3 D PSHgD nd QSHg Y nd otined using
	stenilD s well s for elGny@PSy * AGpEsnqes smple otined using phoE
	tolithogrphy @see setion TFPFPD we indite this smple s S_phot.D in tle TFSAAF

e

  • iFF kopinD vF penneD rF ousselD tFvF heshnvresD iF flnquetD qF gittoD hFhF pongD wFEsF ihrdD nd rF enevierD The Initial Stages of ZnO Atomic Layer Deposition on Atomically Flat In 0.53 Ga 0.47 As SubstratesD xnosle @PHIVA @eptedAF • eF gludelD iF kopin et al. e movle retor for in situ synhrotron xEry hrteristion of erly stges of evh proess @in progressA • iF kopin et al.D sn situ xEry investigtion of ny evh on sn 0.53 q 0.47 es @in progressA

  -ray investigations of catalytic reactions at surfacesF gtlysis odyD volF IRSD noF QERD pges PPH!PPTD PHHWF @gited on pges ivD IV nd PHFA fennett PHHS frin fennettD ihrd wgnoD t frd foosD lter urupp nd wrio q enonF Antimonide-based compound semiconductors for electronic devices: A reviewF olidEtte iletronisD volF RWD noF IPD pges IVUS!IVWSD PHHSF @gited on pge PFA ferger IWTW r fergerF Contact resistance on diused resistorsF sn olidEtte giruits gonfereneF higest of ehnil persF IWTW siii snterntionD volume IPD pges ITH!ITIF siiiD IWTWF @gited on pge IPRFA ferger IWUP rr fergerF Contact resistance and contact resistivityF tournl of the iletrohemil oietyD volF IIWD noF RD pges SHU!SIRD IWUPF @gited on pge IPRFA foihot PHIT F foihotD vF inD wFEsF ihrdD eF grisiD eF ghkerD F gnE telliD F goindeuD F vyD F yuledD gF quihetD wF rF ghuD xF euertD qF gittoD iF flnquetD yF homsD tFEvF heshnvresD hF hF pong nd rF enevierF Evolution of Crystal Structure During the Initial Stages of ZnO Atomic Layer DepositionF ghemF wterFD volF PVD noF PD pges SWP!THHD tnury PHITF @gited on pges PT nd IIQFA foihot PHIT foihotD v inD wEs ihrdD e grisiD e ghkerD gntelliD goindeuD vyD yuledD g quihetet al. Evolution of crystal structure during the initial stages of ZnO atomic layer depositionF ghemistry of wE terilsD volF PVD noF PD pges SWP!THHD PHITF @gited on pges UTD UU nd IIUFA h pong nd grol hompsonF In situ synchrotron x-ray studies of ferroelectric thin lmsF ennuF evF wterF esFD volF QTD pges RQI!RTSD PHHTF @gited on pge PSFA pong PHIH hh pongD te istmnD u uimD pisterD wt righlndD w fldo nd r puossF In situ synchrotron x-ray characterization of ZnO atomic layer depositionF epplied hysis vettersD volF WUD noF IWD pge IWIWHRD PHIHF @gited on pges IUD PSD UT nd VRFA pujimur IWWQ xorifumi pujimurD okihiro xishihrD eiki qotoD tifng u nd ihiro stoF Control of preferred orientation for ZnOx lms: control of self-textureF tournl of grystl qrowthD volF IQHD noF IEPD pges PTW!PUWD IWWQF @gited on pge IIUFA qo PHIT hengning qoD pei uD oon wyungD uixing peiD vindr unjoliD vi ng nd rg fnerjeeF Standing and sitting adlayers in atomic layer deposition of ZnOF tournl of uum iene 8 ehnology eX uumD urfesD nd pilmsD volF QRD noF ID pge HIeIRQD PHITF @gited on pges IRD ITD UUD VUD IHRD IHV nd IIIFA qeorge PHHW teven w qeorgeF Atomic layer deposition: an overviewF ghemil reviewsD volF IIHD noF ID pges III!IQID PHHWF @gited on pges WD IID IPD IHR nd IHVFA qersimhuk PHIR s qersimhukD u vlovskiiD sf oehko nd u nE ghinEynF Thermodynamics of the vaporization of alkyl compounds of zinc, selenium, cadmium, tellurium, and their equimolecular solutionsF ussin tournl of hysil ghemistry eD volF VVD noF QD pges QTS!QUID PHIRF @gited on pge QTFA qeyer PHIP ott w qeyerD ungthiw wethpnonD fonggeun hongD iero e inett nd tey p fentF In Vacuo Photoemission Studies of Platinum Atomic Layer Deposition Using Synchrotron RadiationF he journl of physE il hemistry lettersD volF RD noF ID pges IUT!IUWD PHIPF @gited on pge PSFA qeyer PHIR ott w qeyerD ungthiw wethpnonD ihrd tohnsonD ooE ree uimD hougls q n gmpenD epurv weth nd tey p fentF An atomic layer deposition chamber for in situ x-ray diraction and scattering 172 Bibliography analysisF eview of ienti( snstrumentsD volF VSD noF SD pge HSSIITD PHIRF @gited on pge PSFA qreen PHHP wv qreenD wE roD f fushD qh ilkD orshD hierry gonrdD fert frijsD ilfried ndervorstD s äisänenD h wulleret al. Nucleation and growth of atomic layer deposited HfO 2 gate dielectric layers on chemical oxide (SiOH) and thermal oxide (SiO 2 or SiON) underlayersF tournl of epplied hysisD volF WPD noF IPD pges UITV!UIURD PHHPF @gited on pges IPD UTD VV nd VWFA qrus PHHR u qrusD gi xelsonD xt teinmetz nd w qeorgeF Nucleation and growth during the atomic layer deposition of W on Al2O3 and Al2O3 on WF hin olid pilmsD volF RTUD noF IEPD pges IT!PUD PHHRF @gited on pge IPFA quillemin PHIU ophie quilleminD omin rizeD toseph grettD lentin gntelliD hvid elertiniD frie qutierD qeorges frémondD hillon h pongD ruert enevier nd inent gonsonniF Quantitative and simultaneous analysis of the polarity of polycrystalline ZnO seed layers and related nanowires grown by wet chemical depositionF xnotehnologyD volF PVD noF WD pge HWSUHRD PHIUF @gited on pge WFA quziewiz PHHV i quziewizD se uowlikD w qodlewskiD u uoplkoD ysinniyD e ójikD tsunenkoD i uskowskD szkowiz nd w quziewizF Extremely low temperature growth of ZnO by atomic layer depositionF tournl of epplied hysisD volF IHQD noF QD pge HQQSISD PHHVF @gited on pges IP nd ITFA quziewiz PHIP i quziewizD w qodlewskiD v hnikiD e urjewskiD q vukD qierltowskD tkielD e tonertD visowskiD w urwzyket al. ALD grown zinc oxide with controllable electrical propertiesF emiondutor iE ene nd ehnologyD volF PUD noF UD pge HURHIID PHIPF @gited on pges IHV nd IIIFA rll PHIS hvid rllD uErsin viu nd uErw voF Single photon avalanche detectors: prospects of new quenching and gain mechanismsF xnophotonisD volF RD noF ID pges QWU!RIPD PHISF @gited on pge PFA re PHIR qng reD tun qoD rnshung ghenD tingio guiD hoqi un nd ioshung ghenF Modulating the interface quality and electrical properties of HfTiO/InGaAs gate stack by atomic-layer-deposition-derived Al2O3 passivation layerF eg pplied mterils 8 interfesD volF TD noF PRD pges PPHIQ!PPHPSD PHIRF @gited on pge IUFA red PHIS eshley redD hilpi ghudhryD qiorgi ylivieriD prie fournelD tesper x endersenD prnÌois ohetD tenEtques qllet nd tohim hndtF Near ambient pressure X-ray photoelectron spectroscopy study of the atomic layer deposition of TiO2 on RuO2 (110)F he tournl of hysil ghemistry gD volF IPHD noF ID pges PRQ!PSID PHISF @gited on pge IUFA reyns PHHW wr reyns nd ilmn siF Ultimate scaling of CMOS logic devices with Ge and IIIV materialsF wrs ulletinD volF QRD noF UD pges RVS!RWPD PHHWF @gited on pges iii nd PFA rollinger IWWR qu rollingerD kheytEuni nd w qendryF Oxides on GaAs and InAs surfaces: An x-ray-photoelectron-spectroscopy study of reference compounds and thin oxide layersF hysil eview fD volF RWD noF ITD pge IIISWD IWWRF @gited on pges P nd QFA rölzl IWUW tosef rölzl nd prnz u hulteF Work function of metalsF sn olid urfe hysisD pges I!ISHF pringerD IWUWF @gited on pge IPQFA rung PHHW wv rungD g ghngD r ghngD h vinD t uwo nd w rongF Energy-band parameters of atomic layer deposited Al 2 O 3 and HfO 2 on In x Ga 1-x AsF epplied hysis vettersD volF WRD noF SD pge HSPIHTD PHHWF @gited on pge IUFA rwng PHIQ gheol eong rwngF etomi lyer deposition for semiondutorsF pringerD PHIQF @gited on pge VVFA sshii PHHW riroyuki sshiiD xoriyuki wiytD uji reD ro sttniD etsuji sudD risshi mdD xooru pukuhrD wshiko rtD womoko heurD wskzu ugiymet al. High electron mobility metalinsulator semiconductor eld-eect transistors fabricated on (111)-oriented InGaAs channelsF epplied hysis ixpressD volF PD noF IPD pge IPIIHID PHHWF @gited on pge PFA sshikw IWWQ riroshi sshikwF Theoretical gain of strained quantum well grown on an InGaAs ternary substrateF epplied physis lettersD volF TQD noF TD pges UIP!UIRD IWWQF @gited on pge PFA tohnson PHIR ihrd tohnsonD edm rultqvist nd tey p fentF A brief review of atomic layer deposition: from fundamentals to applicationsF wteE rils todyD volF IUD noF SD pges PQT!PRTD PHIRF @gited on pge IHFA ujikw PHHT uy ujikwF Texture development of non-epitaxial polycrystalline ZnO lmsF tournl of grystl qrowthD volF PVWD noF ID pges QVU!QWRD PHHTF @gited on pge IIUFA uim PHIH eong ueun uimD teong rwn rnD qun rwn uim nd gheol eong rwngF Investigation on the growth initiation of Ru thin lms by atomic layer depositionF ghemistry of wterilsD volF PPD noF WD pges PVSH!PVSTD PHIHF @gited on pges UT nd VVFA uim PHIT eung ryun uimD o eong tooD ryun oo tinD ooEfyoung uim nd e too rkF Ultrathin ZnS and ZnO Interfacial Passivation Layers for Atomic-Layer-Deposited HfO2 Films on InP SubstratesF eg pplied mteE rils 8 interfesD volF VD noF QPD pges PHVVH!PHVVRD PHITF @gited on pges iii nd IUFA ulug PHIS te'rey e ulugD wtthew eimerD tonthn h imeryD engel ngusEqilD önke eifertD ghristin w hlepützD elex fp wrtinsonD tefE frey ilmD edm rok nd homs roslierF A modular reactor design for in situ synchrotron x-ray investigation of atomic layer deposition pro-cessesF eview of ienti( snstrumentsD volF VTD noF IID pge IIQWHID PHISF @gited on pges PS nd UTFA unps PHIQ ujell unps nd wikko itlF In situ studies on reaction mechanisms in atomic layer depositionF gritil reviews in solid stte nd mterils sienesD volF QVD noF QD pges ITU!PHPD PHIQF @gited on pge PRFA unudsen PHIT tn unudsenD tesper x endersen nd tohim hndtF A versatile instrument for ambient pressure x-ray photoelectron spectroscopy: The Lund cell approachF 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uesselsF In situ spectroscopic ellipsometry as a versatile tool for studying atomic layer depositionF tournl of hysis hX epplied hysisD volF RPD noF UD pge HUQHHID PHHWF @gited on pges IU nd PTFA vu IWWU i hing vuD eng ei inD xthn ndlerD uevin e wuinley nd ul u ghuF Evidence that N2O is a stronger oxidizing agent than O2 for the post-deposition annealing of Ta2O5 on Si capacitorsF tpnese journl of pplied physisD volF QTD noF PD pge TTID IWWUF @gited on pge IQFA veskelä PHHQ wrkku veskelä nd wikko itlF Atomic layer deposition chemistry: recent developments and future challengesF engewndte ghemie snterE ntionl iditionD volF RPD noF RSD pges SSRV!SSSRD PHHQF @gited on pge WFA vio PHIQ wEr vio nd Eu ghenF Experimental demonstration on the ultra-low source/drain resistance by metal-insulator-semiconductor contact structure in In0.53Ga0.47As eld-eect transistorsF es edvnesD volF QD noF WD pge HWPIIVD PHIQF @gited on pges IUD IPH nd IPQFA vio PHIS wEr vio nd g vienF The comprehensive study 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Growth mechanism and continuity of atomic layer deposited TiN lms on thermal SiO 2F tournl of pplied physisD volF WPD noF IPD pges UTRI!UTRTD PHHPF @gited on pges UTD VV nd VWFA hller IWWU oert hllerF Moore's law: past, present and futureF siii spetrumD volF QRD noF TD pges SP!SWD IWWUF @gited on pges iiiD P nd WFA ehrist PHHS e ehristD pr preguetteD y reintzD w hungD hg tohnson nd w qeorgeF Optimization and structural characterization of W/Al2O3 nanolaminates grown using atomic layer deposition techniquesF ghemistry of mterilsD volF IUD noF IQD pges QRUS!QRVSD PHHSF @gited on pge IPFA onnet PHII ew onnetD qltgeD u rurleyD i eluhiD u homsD e qoE linskD t rungD x qoelD q fersukerD uirket al. Remote phonon and surface roughness limited universal electron mobility of In 0.53 Ga 0.47 As surface channel MOSFETsF wiroeletroni ingineeringD volF VVD noF UD pges IHVQ!IHVTD PHIIF @gited on pge PFA peight PHHS tmes q peightet al. vnge9s hndook of hemistryF wqrwErill xew orkD PHHSF @gited on pge QIFA tephenson IWWW q frin tephensonD te'rey e istmnD yrlndo euielloD enE neli wunkholmD grol hompsonD ul r puossD ul piniD teven henE frs nd tmes pekF Real-time X-ray scattering studies of surface structure during metalorganic chemical vapor deposition of GaNF w fulE letinD volF PRD noF ID pges PI!PSD IWWWF @gited on pge PSFA un PHHV un unD iero inettD oE ghenD wshru uoyshiD oshio xishiD xiti qoelD wihel qrner nd ilmn siF Arsenic-dominated chemistry in the acid cleaning of InGaAs and InAlAs surfacesF epplied hysis vettersD volF WQD noF IWD pge IWRIHQD PHHVF @gited on pges QD RD UD UT nd WRFA kgi PHIT kgiD w xoguhiD w uimD Er uimD gE ghngD w okoymD u xishiD hngD w ue nd w kenkF III-V/Ge MOS device technologies for low power integrated systemsF olidEtte iletronisD volF IPSD pges VP! IHPD PHITF @gited on pge PFA llrid PHHV wssimo llridD uonstntin urvev nd hieter hmeisserF The initial atomic layer deposition of Hf O 2/ Si (001) as followed in situ by synchrotron radiation photoelectron spectroscopyF tournl of epplied hysisD volF IHRD noF TD pge HTRIITD PHHVF @gited on pge PSFA llrid PHIP wssimo llrid nd hieter hmeisserF In situ ALD experiments with synchrotron radiation photoelectron spectroscopyF emiondutor iene nd ehnologyD volF PUD noF UD pge HURHIHD PHIPF @gited on pge PSFA mmenm IWVS w mmenmD uoskinenD v riltunenD v xiinistö nd w veskeläF Zinc chalcogenide thin lms grown by the atomic layer epitaxy technique using zinc acetate as source materialF hin olid pilmsD volF IPRD noF PD pges IPS!IPVD IWVSF @gited on pge IQFA nsknen PHII tukk nsknenD tonthn fkkeD pni e kknen nd tey p fentF Inuence of organozinc ligand design on growth and material properties of ZnS and ZnO deposited by atomic layer depositionF tournl of uum iene 8 ehnology eX uumD urfesD nd pilmsD volF PWD noF QD pge HQISHUD PHIIF @gited on pge IQFA pily PHIH undr pilyD hiefeng qu nd relmut fumgrtF Growth Mechanism of ALD ZnO Films Investigated by Physical CharacterizationF ig rnstionsD volF QQD noF PD pges QSS!QTQD PHIHF @gited on pge VWFA ung PHHI ymond ungF Recent advances in Schottky barrier conceptsF wE terils iene nd ingineeringX X eportsD volF QSD noF IEQD pges I!IQVD PHHIF @gited on pge IPHFA ynell PHIR ommi ynell nd writ urppinenF Atomic layer deposition of ZnO: a reviewF emiondutor iene nd ehnologyD volF PWD noF RD pge HRQHHID PHIRF @gited on pges ivD WD IPD IQ nd VUFA vn horp PHIQ hennis r vn horpD ophi ernutsD hniel guypersD tens ipD prnk rolsteyns nd tefn he qendtF Wet chemical etching of InGaAs for Advanced CMOS ProcessingF ig rnstionsD volF SVD noF TD pges PVI!PVUD PHIQF @gited on pges T nd UFA vn horp PHIR hennis r vn horpD ophi ernutsD hniel guypersD tens ipD prnk rolsteynsD tefn he qendt nd tohn t uellyF Nanoscale Etching of In0.53Ga0.47As in H2O2/HCl Solutions for Advanced CMOS ProcessingF ig tournl of olid tte iene nd ehnologyD volF QD noF TD pges IUW!IVRD PHIRF @gited on pges T nd UFA vn horp PHIS hennis r vn horpD ophi ernutsD prnk rolsteyns nd tefn he qendtF Wet-Chemical Approaches for Atomic Layer Etching of Semiconductors: Surface Chemistry, Oxide Removal and Reoxidation of InAs (100)F ig tournl of olid tte iene nd ehnologyD volF RD noF TD pges xSHTI!xSHTTD PHISF @gited on pge TFA gner IWUH tohn gnerF Preparation and Properties of Bulk In1-x Ga x As AlloysF tournl of he iletrohemil oietyD volF IIUD noF WD pges IIWQ!IIWTD IWUHF @gited on pge PFA lle PHHW oert w lleD ul g wsntyreD tiyoung uim nd oshio xishiF Atomic layer deposition of dielectrics on Ge and IIIV materials for ultrahigh performance transistorsF w ulletinD volF QRD noF UD pges RWQ!SHQD PHHWF @gited on pge IUFA ng PHIT ghong ngD hoying ueD eid ruD tie ng nd u ngF Review of Quantum Dot-in-a-Well Infrared Photodetectors and Prospect of New StructuresF tournl of xnosiene nd xnotehnologyD volF ITD noF VD pges VHRT!VHSRD PHITF @gited on pge PFA tnuki PHHW uohei tnukiD rirokzu eshrD etsutoshi snokuhiD kumi udotD ghihiro rsegwD riroki untoD ekinou ermotoD suyuki hiri nd dhiro yhmiF Thermal Decomposition Characteristics of Metalorganic Materials of Zinc Oxide for Evaluation as MOCVD PrecursorF sn weeting estrtsD numer ISD pges UHQ!UHQF he iletrohemil oietyD PHHWF @gited on pge RQFA ekmn PHIV imo ekmn nd uri irik vsonenF Atomic Layer Deposition of Zinc Oxide: Study on the Water Pulse Reactions from First PrinciplesF he tournl of hysil ghemistry gD PHIVF @gited on pge ISFA ind PHHW indD pr preguetteD e ehrist nd w qeorgeF Nucleation period, surface roughness, and oscillations in mass gain per cycle during W atomic layer deposition on Al 2 O 3F tournl of epplied hysisD volF IHSD noF UD pge HURQHWD PHHWF @gited on pge IPFA oolley IWTV tohn g oolleyD wthew f homs nd eln q hompsonF Optical energy gap variation in GaxIn1-x As alloysF gndin tournl of hysisD volF RTD noF PD pges ISU!ISWD IWTVF @gited on pge PFA un PHHU unD uD rg vinD hen nd h e eideF Submicrometer Inversion-Type Enhancement-Mode InGaAs MOSFET With Atomic-Layer-Deposited Al 2 O 3 as Gate DielectricF siii iletron hevie vettersD volF PVD noF IID pges WQS!WQVD PHHUF @gited on pge IUFA un PHHU unD uD henD ng nd h eF High performance submicron inversion-type enhancement-mode InGaAs MOSFETs with ALD Al 2 O 3 , HfO 2 and HfAlO as gate dielectricsF sn iletron hevies weetingD PHHUF sihw PHHUF siii snterntionlD pges TQU!TRHF siiiD PHHUF @gited on pge IUFA e PHHR h eD qh ilkD f ngD t uwoD rEtv qossmnnD w rongD uu xg nd t fudeF Depletion-mode InGaAs metal-oxide-semiconductor eld-eect transistor with oxide gate dielectric grown by atomic-layer depositionF epplied hysis vettersD volF VRD noF QD pges RQR!RQTD PHHRF @gited on pge IUFA en PHHW uuoEi enD uungEi viuD enEing vinD tyhEong qongD uuenEu siD hongEun vyuD iEun vinD hihEghng vingD quoEu xi nd prEen tihF On the Characteristics of Zinc Oxide Films Grown on (11-20) Sapphire Substrates by Atomic Layer Deposition Using Diethylzinc and Nitrous OxideF ig rnstionsD volF IWD noF PD pges VRQ!VSQD PHHWF @gited on pge IPFA im PHHV ungEoo imD hoEtoong veeD uiEu uimD ooEryun uimD eEik oon nd uiEfum uimF Nucleation kinetics of Ru on silicon oxide and silicon nitride surfaces deposited by atomic layer depositionF tournl of epplied hysisD volF IHQD noF IID pge IIQSHWD PHHVF @gited on pge VWFA ous( PHHH il fekkye ous(D tques pouhe nd hniel vinotF Study of atomic layer epitaxy of zinc oxide by in-situ quartz crystal microgravime-tryF epplied surfe sieneD volF ISQD noF RD pges PPQ!PQRD PHHHF @gited on pges W nd ISFA hiou PHIT eifeddine hiouF Réaction à l'état solide d'un lm mince de Ni (Co) avec InGaAs: analyses microstructuralesF hh thesisD qrenole elpesD PHITF @gited on pge IIWFA unigEerez PHIT tesus unigEerezD inent gonsonniD viverios vymperkisD ing uongD ehim rmpertD ergio pernndezEqrridoD yliver frndtD ruert enevierD ti uellerD urine 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	sistors for high frequency applicationsF uperltties nd wirostruturesD volF VTD pges I!IWD PHISF @gited on pge PFA hevlooEgsier PHIR uilin hevlooEgsierD url p vudwigD ghristophe hetvernier glwson PHHI e glwsonF Guide to references on IIIV semiconductor chemical nd tolien hendoovenF In situ synchrotron based x-ray techniques as moni-etchingF wterils iene nd ingineeringX X eportsD volF QID noF IETD pges I!RQVD PHHIF @gited on pge TFA toring tools for atomic layer depositionF tournl of uum iene 8 ehE elm PHHQ we elm nd wv qreenF Mathematical description of atomic layer nology eX uumD urfesD nd pilmsD volF QPD noF ID pge HIHVHID PHIRF deposition and its application to the nucleation and growth of HfO 2 gate dielectric layersF tournl of pplied physisD volF WRD noF SD pges QRHQ!QRIQD PHHQF @gited on pge SRFA elsExielsen PHII tens elsExielsen nd hes wworrowF ilements of modern xEry physisF tohn iley 8 onsD PHIIF @gited on pges WS nd WUFA emeen PHIR whmoud emeenD vur xynsD onj ionkeD hennis vinD s svnovD hierry gonrdD tohn weersshutD w petehD ven n ilshoht nd ennelies helieF Al2O3/InGaAs metal-oxide-semiconductor interface prop-erties: Impact of Gd2O3 and Sc2O3 interfacial layers by atomic layer depo-sitionF ig tournl of olid tte iene nd ehnologyD volF QD noF IID pges xIQQ!xIRID PHIRF @gited on pge IUFA fji PHIP só( fjiD oltán vádiD solt i rorváthD qyörgy wolnárD tános olkD sstván fársony nd éter frnF Nucleation and growth modes of ALD ZnOF grystl qrowth 8 designD volF IPD noF IID pges STIS!STPHD PHIPF @gited on pges UTD VV nd IITFA flmes PHHW y flmesD n ijnD h ermeilleD e estD v etitD r ssernD hufrne nd peliiF The ID03 surface diraction beamline for in-situ tournl of hysisX gondensed wtterD volF PD noF QD pge UHID IWWHF @gited on pge UUFA ghng PHIS gE ghngD y shikwD ysdD w rtD r mdD w kenk nd kgiF Impact of La2O3 interfacial layers on InGaAs metal-oxide-semiconductor interface properties in Al2O3/La2O3/InGaAs gate stacks de-posited by atomic-layer-depositionF tournl of epplied hysisD volF IIVD noF VD pge HVSQHWD PHISF @gited on pge IUFA ghson PHIT iri ghson nd rdeep quduruF Tutorial: Understanding resid-ual stress in polycrystalline thin lms through real-time measurements and physical modelsF tournl of epplied hysisD volF IIWD noF IWD pge IWIIHID PHITF @gited on pge PVFA ghen PHIQ viu ghenD hng uEwingD hng iEwen nd vü rongEvingF In-terfacial characteristics of Al/Al2O3/ZnO/n-GaAs MOS capacitorF ghinese hysis fD volF PPD noF UD pge HUTUHID PHIQF @gited on pges iii nd IUFA gho PHHR woonju ghoD hoo eok teongD tehoo rkD rong fe rkD uk oo gohen IWVP imon gohenF Contact resistance and methods for its determinationF w ynline roeedings virry erhiveD volF IVD IWVPF @gited on pge IPRFA gonnelly PHHR hniel gonnellyD grl pulknerD hi qrupp nd t rrrisF A new route to zero-barrier metal source/drain MOSFETsF siii rnstions on xnotehnologyD volF QD noF ID pges WV!IHRD PHHRF @gited on pges IPHD IPP nd IPQFA grook PHHU edm w grookD irik vindD h qri0thD wrk t odwellD teremy h immermnD erthur g qossrd nd eth fnkF Low resistance, nonalloyed Ohmic contacts to InGaAsF epplied hysis vettersD volF WID noF IWD pge IWPIIRD PHHUF @gited on pge IPQFA guypers PHIR hniel guypersD hennis r n horpD wssimo llridD imone frizziD hierry gonrdD veonrd xt odriguezD wrten weesD ophi erE nutsD hieter hmeisserD ghristoph edelmnnet al. Study of InP surfaces after wet chemical treatmentsF ig tournl of olid tte iene nd ehE nologyD volF QD noF ID pges xQHIT!xQHPPD PHIRF @gited on pge SFA hel elmo PHII tesús e hel elmoF Nanometre-scale electronics with IIIV com-@gited on pge PRFA hevlooEgsier PHIT uilin hevlooEgsierD ieter qeiregtD url p vudwigD uoen vn tiphoutD endreÌ ntommeD eger rensD ghristophe hetvernier nd tolien hendoovenF A case study of ALD encapsulation of quantum dots: Embedding supported CdSe/CdS/ZnS quantum dots in a ZnO matrixF he tournl of hysil ghemistry gD volF IPHD noF QPD pges IVHQW!IVHRSD PHITF @gited on pge PSFA hiehl PHHQ olnd hiehlF righEpower diode lsersX fundmentlsD tehnologyD pE plitionsD volume UVF pringer iene 8 fusiness wediD PHHQF @gited on pge PFA ilm PHHI t ilmD gi xelsonD u qrus nd w qeorgeF Nucleation and growth during tungsten atomic layer deposition on SiO2 surfacesF hin olid pilmsD volF QVTD noF ID pges RI!SPD PHHIF @gited on pges IPD UT nd VVFA ilm PHHQ t ilm nd w qeorgeF Growth of ZnO/Al2O3 alloy lms using atomic layer deposition techniquesF ghemistry of wterilsD volF ISD noF RD pges IHPH!IHPVD PHHQF @gited on pges IR nd ISFA and real-time Xfrouder IWWH ghristin frouderF Angular dependence of X-ray absorption spectraF veeD e too rkD gheol eong rwngD qi roon tng nd tehk teongF pound semiconductorsF xtureD volF RUWD noF UQUQD pge QIUD PHIIF @gited on png PHII rui pngD worten wdsenD grlo grrroD uunihru keiD r ul
	Comparison between atomic-layer-deposited HfO 2 lms using O 3 or H 2 O pges iii nd PFA uimD ilen lisD zuEing ghenD njy urishnD uEvun ghuehD oy

2.3.1 Water evaporator . . . . . . . . . . . . . . . . . . . . . . . . . 30

4.4 Island growth modeling . . . . . . . . . . . . . . . . . . . . . . 84 4.5 Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87 4.6 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90

pigure fFQX gontrol pnelX dministrtor windowF

Acknowledgments

wetlEyxideEemiondutor pieldEi'et rnsistor MS: wetlEemiondutor OM: yptil wirosope PEEK: olyether ither uetone PES: hotoEiletron petrosopy PhVD: hysil por heposition PLD: ulsed vser heposition PSD: ower petrl hensity PTA: pstrem ehnologil ltform PVD: lsm por heposition

Appendix A

The In 0.47 Ga 0.53 As roughness change as a function of the etching time he series of the snqes smples were ethed in rgl solution with di'erent onenE trtionsF he prmeters of ething nd time re demonstrted in leF eFIF eries of epw imges were otined for sn 0.53 q 0.47 es smplesF he smples were ethed in HFIw rglXHFHHI r 2 y 2 solution for di'erent ething time t etching F efter the smples were rinsed in r 2 y for QH sec nd dried with x 2 F he epw imges @pigF eFI@EfAA nd ross setions of sn 0.53 q 0.47 es epw imges @pigF eFPA demonstrte roughness inrese y inresing ething timeF he roughness were inresed from HFHS nm pigure eFIX sn 0.53 q 0.47 es surfe epw imges for di'erent smples ethed in HFIw rglXHFHHIw r 2 y 2 solution during Q min @AD T min @AD W min @AD IP min @dAD IS min @eA nd IV min @fAF efter smples were rinsed in r 2 y for QH sec nd dried with x 2 F @re sustrteA to HFQS nm @t etching aIV minAF he results for roughness vs ething time shown on pigF eFQF st is possile to inrese sn 0.53 q 0.47 es surfe roughness Appendix A. pigure fFSX Qh rendering of the sme epw imges shown in pigF RFRD i.e. postE growth epw imges of ny (lms grown on sn 0.53 q 0.47 es for di'erent numer of ylesX H @AD S @AD IH @AD IS @dAD PH @eAD PS @fAD QH @gAD RH @hA nd SH @iAF pigure fFTX ttistil distriution of the terre heights present on the sn 0.53 q 0.47 es sustrte surfe fter the Rw rgl eth stepF he height vlue is in unitsD where is the ulk sn 0.53 q 0.47 es lttie prmeterF e series of prllel lines were hosen with onstnt distne etween the lines for the nlysisF he peks of the sttistil distriution hve een pproximted y qussin funtionF pigure fFUX n u α Ery )uoresene intensity @ substrate a IPH • gA vs. yle numE er for three di'erent wter )ow @deionized wterAF he inresing of wter )ow is otined y opening the injetor perture @PD TD W re the numers of turns of the mnul needle vlveAF glerlyD inresing the wter )ow shortens the dely in ny nuletionF 155 pigure fFVX sE urves mesured y four point proe mesurement for nonEethed elGnyGnEsnqes with di'erent thikness of ny lyerD the thikness of the ny lyer is presented y the deposition ylesX @A PH ylesY @A PS ylesY @A QH ylesY @dA RH ylesY @eA SH yles pigure fFWX sE urve mesured y four point proe mesurement for nonEethed elGnyGpEsnqes with di'erent thikness of ny lyerD the elGpEsnqes s refereneD the thikness of the ny lyer is presented y the deposition ylesX @A no nyY @A PH ylesY @A PS ylesY @dA QH ylesY @eA RH ylesY @fA SH ylesF pigure fFIHX sE urve mesured y four point proe mesurement for elGnyGpE snqes t with di'erent thikness of ny lyer fter rxy 3 ething tretmentD the elGpEsnqes s refereneD the thikness of the ny lyer is presented y the deposition ylesX @A no nyY @A PH ylesY @A PS ylesY @dA QH ylesY @eA RH ylesY @fA SH yles

Conferences, workshops, and publications

Conferences and workshops

Summary

prior to Qh growth eginsF st is very likely tht the wter )ow ontrols the denE sity of hydroxyl groups on the snqes surfeF e lso demonstrted ny evh for di'erent snqes sustrte temperturesF fy omining in situ Ery sorpE tion nd grzing inidene sttering tehniquesD we identi(ed shortErngeEorder tomi struture of the ny mterilD with n emryoni ny wurtziteD prior to Qh growthD then longErngeEorder struture is deteted oth y Ery sorption nd Ery di'rtionD together with the pperne of mirostrutureF et higher growth tempertureD outside of the evh windowD we oserved the wellEknown ny texturing when the lyer thikness inresesF et lstD we report on the use of ultrthin ny lyers on snqes in the eletriE l ontt strutureF he ontt resistne of metlGnyGsnqes smples ws mesured using rnsfer vength wethod @vwAF e show tht spei( ontt reE sistivity of elGpEsnqes pds is redued y inserting ny tunnel lyer in etween el nd pEdoped snqesF Keywords: yxide thin (lmD etomi vyer hepositionD edvned struturl hrteriztionD ynhrotron rditionD ynhrotron rdition