Lorenzo Bottiglieri

Abderrahime Sekkat

Mouncif Belmouhoub

João Resende

Viet Huong Nguyen

Matthieu Weber

David Munoz Rojas

Carmen Jiménez

Jean-Luc Deschanvres

n-ZnO/Out-of-stoichiometry p-CuCrO2 diodes for efficient and lowcost transparent electronic applications

Keywords: chemical deposition methods, transparent electronics, transparent p-n junctions, MOCVD, Spatial ALD, thin films

In this work, we present the synthesis of high-performance transparent diodes based on ptype out of stoichiometry CuCrO2 and n-type ZnO thin films. The oxides were fabricated by scalable chemical deposition methods at low temperature and ambient pressure, without any further post-deposition annealing treatment. We report the optimization of the devices through the fine-tuning of the deposition parameters of the two layers, namely, the composition of the p-type semiconductor and the deposition temperature of the n-type counterpart, and their thorough characterization. UV-VIS spectroscopy measurements highlighted the antireflection function of the ZnO layer, resulting in a transmittance of the junction above 75% in the visible range. In-depth XPS profile studies confirmed the absence of atomic diffusion between the different layers. The optimized junction between a nanocomposite Cu2O+CuCrO2 coupled with polycrystalline ZnO presents the highest rectification ratio reported in the literature for similar devices, with values greater than 10 5 between -2.5 V and +2.5 V. These extremely high performances are attributed to the formation of intraband levels, due to the stoichiometry variation of the CuCrO2 phase and the low crystallinity of n-type ZnO. These results open many prospects for optoelectronics and are particularly promising for the transparent oxide electronics industry.

Introduction

The production of transparent and performant all-oxide p-n junctions fabricated through low-cost processes represent one of the greatest challenges for the transparent electronics industry. The versatility of such devices, which can be applied as diodes, photo detectors [START_REF] Zhai | A comprehensive review of one-dimensional metal-oxide nanostructure photodetectors[END_REF][START_REF] Cossuet | ZnO/CuCrO2 Core-Shell Nanowire Heterostructures for Self-Powered UV Photodetectors with Fast Response[END_REF] , transparent solar cells [START_REF] Fortunato | Oxide Semiconductor Thin-Film Transistors: A Review of Recent Advances[END_REF][START_REF] Granqvist | Transparent conductors as solar energy materials: A panoramic review[END_REF][START_REF] Kim | Transparent Thin-Film Silicon Solar Cells for Indoor Light Harvesting with Conversion Efficiencies of 36% without Photodegradation[END_REF] , and light-emitting diodes [START_REF] Liu | Transparent conducting oxides for electrode applications in light emitting and absorbing devices[END_REF] , justifies the growing interest in this field. Various metal oxides have been integrated as active and passive components in the previously mentioned devices. In this framework, one of the limiting factors is the lack of highly conductive p-type transparent conductive oxides (TCOs) and issues related to the low energy of the valence bands [START_REF] Yim | Computational discovery of p-type transparent oxide semiconductors using hydrogen descriptor[END_REF] . Among promising p-type oxide semiconductor materials, Cu2O [START_REF] Abdelfatah | Fabrication and characterization of low cost Cu2O/ZnO:Al solar cells for sustainable photovoltaics with earth abundant materials[END_REF] and NiO [START_REF] Sato | Transparent conducting p-type NiO thin films prepared by magnetron sputtering[END_REF] were successfully applied in optoelectronic devices [START_REF] Sekkat | Open-air printing of Cu2O thin films with high hole mobility for semitransparent solar harvesters[END_REF][START_REF] Nguyen | Open-air, low-temperature deposition of phase pure Cu2O thin films as efficient hole-transporting layers for silicon heterojunction solar cells[END_REF][START_REF] Steirer | Solution deposited NiO thin-films as hole transport layers in organic photovoltaics[END_REF] . Nevertheless, they suffer from various limitations, hindering their widespread application. For instance, Cu2O presents limited transparency, with a corresponding bandgap around 2.2 eV [START_REF] Resende | Magnesium-doped cuprous oxide (Mg:Cu2O) thin films as a transparent p-type semiconductor[END_REF] , whereas NiO is characterized by a small carrier mobility [START_REF] Kaya | Highly efficient tandem photoelectrochemical solar cells using coumarin6 dye-sensitized CuCrO2 delafossite oxide as photocathode[END_REF][START_REF] Kavan | Electrochemistry and dye-sensitized solar cells[END_REF] . Therefore, more research efforts are required to obtain novel more efficient p-type TCOs.

CuCrO2 is considered a promising p-type TCO for efficient p-n junctions due to its relatively high conductivity, around 1 Ω.cm for the stoichiometric compound [START_REF] Tripathi | Atomic layer deposition of transparent semiconducting oxide CuCrO2 thin films[END_REF] , and good transparency, around 70% in the visible range [START_REF] Tripathi | Atomic layer deposition of transparent semiconducting oxide CuCrO2 thin films[END_REF] . Various deposition methods have been used for its synthesis, such as pulsed laser deposition (PLD) [START_REF] Chiu | Preparation of transparent p-CuCrO2:Mg/n-ZnO heterojucntion with in situ laser anealing[END_REF] , RF magnetron sputtering [START_REF] Chen | Fabrication of Transparent CuCrO2:Mg/ZnO p-n Junctions Prepared by Magnetron Sputtering on an Indium Tin Oxide Glass Substrate[END_REF] , metal-organic chemical vapor deposition (MOCVD) [START_REF] Crêpellière | Transparent conductive CuCrO2 thin films deposited by pulsed injection metal organic chemical vapor deposition: Up-scalable process technology for an improved transparency/conductivity trade-off[END_REF][START_REF] Popa | Electrical and optical properties of Cu-Cr-O thin films fabricated by chemical vapour deposition[END_REF][START_REF] Mahapatra | Low-pressure metal-organic CVD of transparent and p-type conducting CuCrO2 thin films with high conductivity[END_REF] , spray pyrolysis [START_REF] Farrell | Spray pyrolysis growth of a high figure of merit, nano-crystalline, p-type transparent conducting material at low temperature[END_REF][START_REF] Farrell | Synthesis of nanocrystalline Cu deficient CuCrO2a high figure of merit p-type transparent semiconductor[END_REF][START_REF] Chikoidze | Control of p-type conduction in Mg doped monophase CuCrO2 thin layers[END_REF][START_REF] Sánchez-Alarcón | Ultrasonic spray-pyrolyzed CuCrO2 thin films[END_REF] (SP), atomic layer deposition (ALD) [START_REF] Tripathi | Atomic layer deposition of transparent semiconducting oxide CuCrO2 thin films[END_REF] , sol gel [START_REF] Götzendörfer | Influence of single layer thickness on the performance of undoped and Mg-doped CuCrO2 thin films by sol-gel processing[END_REF][START_REF] Götzendörfer | Preparation of CuAlO2 and CuCrO2 thin films by sol-gel processing[END_REF] , and hydrothermal synthesis [START_REF] Jeong | P-Type CuCrO2 particulate films as the hole transporting layer for CH3NH3PbI3 perovskite solar cells[END_REF] . Different reports highlighted the enhancement of the optical and electrical properties of CuCrO2 by tuning the stoichiometry of this material [START_REF] Crêpellière | Transparent conductive CuCrO2 thin films deposited by pulsed injection metal organic chemical vapor deposition: Up-scalable process technology for an improved transparency/conductivity trade-off[END_REF][START_REF] Farrell | Synthesis of nanocrystalline Cu deficient CuCrO2a high figure of merit p-type transparent semiconductor[END_REF][START_REF] Bottiglieri | Out of stoichiometry CuCrO2 films as a promising p-type TCO for transparent electronics[END_REF][START_REF] Sidik | Structures and characteristics of delafossite CuCr1-xO2 thin films prepared by pulsed laser deposition[END_REF] , with the lowest resistivity among non stoichiometric films, around 0.01 Ω.cm, achieved for Cu-poor compounds, Cu0.66Cr1.33O2, synthesized by dynamic liquid-injection MOCVD (DLI-MOCVD) [START_REF] Lunca-Popa | Tuning the electrical properties of the p-type transparent conducting oxide Cu1-xCr1+xO2 by controlled annealing[END_REF] . Furthermore, previous works reported the successful integration of this material in a wide range of applications such as organic [START_REF] Wang | Combustion Synthesis of p-Type Transparent Conducting CuCrO2+ x and Cu:CrOx Thin Films at 180 °C[END_REF] , perovskite [START_REF] Zhang | Low-Temperature Solution-Processed CuCrO2 Hole-Transporting Layer for Efficient and Photostable Perovskite Solar Cells[END_REF][START_REF] Gil | CuCrO2 nanoparticles incorporated into PTAA as a hole transport layer for 85°C and light stabilities in perovskite solar cells[END_REF] , and dye-sensitized solar cells [START_REF] Dimple | Dye Anchoring on CuCrO2 Surfaces for p-Type Dye-Sensitized Solar Cell Applications: An Ab Initio Study[END_REF][START_REF] Xiong | Hydrothermal synthesis of ultrasmall CuCrO2 nanocrystal alternatives to NiO nanoparticles in efficient p-type dye-sensitized solar cells[END_REF] , photodetectors [START_REF] Cossuet | ZnO/CuCrO2 Core-Shell Nanowire Heterostructures for Self-Powered UV Photodetectors with Fast Response[END_REF][START_REF] Ahmadi | An All-sputtered Photovoltaic Ultraviolet Photodetector Based on Co-doped CuCrO2 and Al-doped ZnO Heterojunction[END_REF][START_REF] Li | A Solution-Processed Hole-Transporting Layer Based on p-Type CuCrO2 for Organic Photodetector and Image Sensor[END_REF] , gas sensor [START_REF] Tong | Oxygen vacancy defects boosted high performance p-Type delafossite CuCrO2 gas sensors[END_REF][START_REF] Zhou | Room temperature ozone sensing properties of p-type CuCrO2 nanocrystals[END_REF] , photocatalytic devices [START_REF] Creissen | Inverse Opal CuCrO2 Photocathodes for H2 Production Using Organic Dyes and a Molecular Ni Catalyst[END_REF] , and Q-switched fiber laser [START_REF] Xu | Enhancing Q-Switched Fiber Laser Performance Based on Reverse Saturable and Saturable Absorption Properties of CuCrO2 Nanoparticle-Polyimide Films[END_REF] .

ZnO is considered a promising n-type TCO for transparent electronics [START_REF] Ajimsha | Transparent p-AgCoO2/n-ZnO diode heterojunction fabricated by pulsed laser deposition[END_REF][START_REF] Siol | Band Alignment Engineering at Cu2O/ZnO Heterointerfaces[END_REF][START_REF] Giusti | High performance ZnO-SnO2:F nanocomposite transparent electrodes for energy applications[END_REF] owing its wide direct band gap, around 3.4 eV, its high electron mobility, around 200 cm²V -1 s - 1 47 , together with the possibility to be synthesized at low temperature using solution-based and other soft scalable methods [START_REF] Nguyen | Deposition of ZnO based thin films by atmospheric pressure spatial atomic layer deposition for application in solar cells[END_REF][START_REF] Bhachu | Aerosol assisted chemical vapor deposition of transparent conductive zinc oxide films[END_REF][START_REF] Hoye | Research Update: Atmospheric pressure spatial atomic layer deposition of ZnO thin films: Reactors, doping, and devices[END_REF] . The coupling of p-CuCrO2 with n-ZnO has been previously reported for the fabrication of transparent diodes [START_REF] Tonooka | Preparation of transparent CuCrO2:Mg/ZnO p-n junctions by pulsed laser deposition[END_REF] . To evaluate the electrical performances of these devices, the rectification ratio (Ion/Ioff) is generally considered to be a fundamental criterion. This parameter is defined as the ratio between the current measured at positive voltage, and the one measured at negative bias. On one hand, various works reported the deposition of such devices by physical deposition methods, employing either high temperatures or low pressure, and generally requiring a post-deposition treatment. The transparent p-n junctions fabricated using such techniques showed a rectification ratio, Ion/Ioff, with the highest value ever reported being 120 at ±5 V [START_REF] Chiu | Fabrication of transparent CuCrO2:Mg/ZnO p-n junctions prepared by pulsed laser deposition on glass substrate[END_REF] . On the other hand, different works reported the fabrication of CuCrO2/ZnO-based p-n junctions by chemical routes and a summary of the obtained results is reported in Table 1. The use of solution-based processes implies various fabrication advantages, such as the reduction of the used deposition temperature, ambient pressure and affordable surface scalability [START_REF] Liu | Reaction Pathway of the Hydrothermal Synthesis of AgCuO2from in Situ Time-Resolved X-ray Diffraction[END_REF] , both promising aspects for the industrialization of such devices. Nevertheless, the rectification ratio obtained is one order of magnitude lower than for physical deposition methods. The other chemical approaches reported (MOCVD and SP) involve high deposition temperatures and again the rectification ratios obtained are lower than for diodes obtained by physical deposition methods. Thus, there is a need to develop new chemical processes at low temperature yielding high rectification rations for diodes based on ZnO and CuCrO2. The reported information are the CuCrO2 and ZnO technique and growth temperature, the structure of the device, used annealing conditions (here '/' corresponds to no annealing step, TA corresponds to Thermal annealing, RT corresponds to room temperature, while NR stands for not reported), and the reference.

In our previous work [START_REF] Bottiglieri | Out of stoichiometry CuCrO2 films as a promising p-type TCO for transparent electronics[END_REF] , we investigated the effect of the cationic ratio i.e. Cu/(Cu+Cr) over the properties of the films CuCrO2 and we observed enhanced functional properties for Cu-rich CuCrO2 film with an optimal film composition in the 60 -70% range, named out of stoichiometry films from now on. Thus non stoichiometric films and nanocomposite films, consisting in a mixture of Cu2O and CuCrO2 phases, were obtained by aerosol-assisted metal-organic chemical vapour deposition [START_REF] Bottiglieri | Optimized Stoichiometry for CuCrO2 Thin Films as Hole Transparent Layer in PBDD4T-2F:PC70BM Organic Solar Cells[END_REF] (AA-MOCVD), thus with no vacuum being involved, at only 350° C and showed an optical transmittance of around 55% and resistivity values of 0.1 Ω.cm for film with a composition Cu/(Cu+Cr) of 63% [START_REF] Bottiglieri | Out of stoichiometry CuCrO2 films as a promising p-type TCO for transparent electronics[END_REF] . In the literature there are few reports about the integration of non-stoichiometric CuCrO2 for diode applications. Only Afonso et al. [START_REF] Afonso | Transparent p-Cu0.66Cr1.33O2/n-ZnO heterojunction prepared in a five-step scalable process[END_REF]

O

In this work, we aimed to investigate the feasibility of this p-type semiconductor for diode application. Out of stoichiometry CuCrO2 thin films were coupled with ZnO layers synthesized using atmospheric pressure spatial atomic layer deposition [START_REF] Huong | Impact of precursor exposure on process efficiency and film properties in spatial atomic layer deposition[END_REF] (AP-SALD, a faster, more scalable approach to ALD [START_REF] Muñoz-Rojas | Spatial atmospheric atomic layer deposition: A new laboratory and industrial tool for low-cost photovoltaics[END_REF] ) to fabricate planar heterojunctions using low-temperature (≤ 350 °C) and scalable methods and without any post-deposition treatment. An ITO covered glass was selected as substrate for its suitability for industrial applications. The properties of the p-type TCO were tuned through the control of its stoichiometry and correlated to the performance of the heterojunctions. Besides, the effect of the deposition temperature of the ZnO thin film was also investigated. The optimized devices show a record-breaking Ion/Ioff ratio, evaluated between -2,5V and 2.5V, with a high transparency in the visible. , in the following X, was varied from 50% to 80%. The choice of this concentration range is based on our previous work [START_REF] Bottiglieri | Out of stoichiometry CuCrO2 films as a promising p-type TCO for transparent electronics[END_REF] , and yields CuCrO2 thin films with the best optical-electrical properties. Ethylenediamine (C2H8N2, Sigma Aldrich), with a concentration of 20 mM, was added to improve the solubility of the precursors in the solvent used. During the deposition, the temperature of the substrates was set to 350 °C. Dried compressed air was used as reactive and carrier gasses with a total flow rate of 4000 sccm. Further information about the used reactor can be found somewhere else [START_REF] Bottiglieri | Out of stoichiometry CuCrO2 films as a promising p-type TCO for transparent electronics[END_REF] . For the device's fabrication, CuCrO2 films were deposited over a 1.5 x 1.5 cm² area on the ITO covered glass.

Material and methods

The ZnO thin films were simultaneously deposited on corning glass 1737, used as references, and on top of the ITO/CuCrO2 structures on a surface of 0.75 cm² by using a shadow mask employing a custom-built SALD system [START_REF] De La Huerta | Gas-Phase 3D Printing of Functional Materials[END_REF] . The distance between the substrate and the SALD injection head was approximately 150 µm with a scanning speed of 10cm/s. Diethylzinc precursor (C2H5)2Zn (DEZ) was used to deposit ZnO, using a flow of 30 sccm with 150 sccm of H2O, respectively diluted in 270 and 300 sccm of N2. The N2 barrier total flow was 900 sccm. The deposition temperature was varied between 100 °C, 150 °C, and 200 °C. The number of ALD cycles was varied ensuring similar ZnO thicknesses at different deposition temperatures. The devices were completed by depositing circular Au contacts by thermal evaporation using an EDWARDS FTM6 evaporator, with a current of 4 A for 3 minutes, keeping the chamber pressure at 1x10 -5 Pa. The effective area of the final devices was around 0.04 mm².

The electrical properties of the individual layers were measured by the linear 4-probe method, through at least 5 testing points to obtain an average value for the sheet resistance. The room temperature transport properties of the materials were obtained with a Hall-effect system using a magnetic field of 0.5 T. X-ray diffraction (XRD) patterns were obtained using a Bruker D8 Advance diffractometer in Bragg-Brentano configuration (θ-2θ) with Cu Kα1 radiation (λ=1.54 Ǻ).

Device characterization

Raman spectroscopy was performed at room temperature with a Jobin Yvon/ Horiba LabRam spectrometer equipped with a liquid nitrogen-cooled charge-coupled detector. Raman spectra were collected in the 50-1000 cm -1 frequency range. A blue laser with a wavelength of 488 nm and a power of 0.4 mW at the sample surface was focalized for 10 min to obtain these spectra. This characterization was performed by using a spot size of around 1 μm 2 obtained by using a 100× objective.

Grazing Incidence X-ray Diffraction (GIXRD) acquisitions were collected at the range 20-70° with a step of 0.06° on a RIGAKU Smartlab equipped with a 9-kW rotating anode Cu source (45 kV and 200 mA). TEM cross-section observations were performed to measure the thickness of the films on a JEOL 2010 LaB6. Selected area diffraction (SAED) was performed on the same apparatus. For this characterization, the devices were prepared by the formation of a substrate/device/glue/device/substrate architecture, followed by mechanical polishing and Argon gun sputtering until the perforation of the interface.

The optical properties of the devices were analyzed through UV-VIS-IR spectroscopy on a Lambda 950 spectrophotometer from Perkin Elmer equipped with an integrated sphere, using a wavelength step of 5 nm in the 250 to 1000 nm range. Depth-profile X-ray photoelectron spectroscopy (XPS) measurements were used to evaluate the chemical composition of the device. The C 1s, Zn 2p, Cu 2p, Cr 2p, and O 1s energy regions were scanned using a K-alpha spectrometer from Thermo Fisher Scientific equipped with an Al Xray source (1486.6 eV). A Depth profile analysis was carried out by measuring after successive 30 s Ar etchings (2 keV).

Current-voltage measurements were made using tungsten tips connected to a Keithley 2400 source meter, sweeping the voltage among ±2.5 V with a step of 0.06 V, and recording the corresponding current. A minimum of three diodes were tested for each configuration, with a minimum of two measurements for each device. The diode parameters were extracted using 2-3 Diode Fit software by nano-HUB, following the classic diode equation:

𝐼 = 𝐼 0 (𝑒 𝑞(𝑉-𝐽𝑅 𝑠 ) 𝜂𝑘 𝐵 𝑇 -1) + 𝑉 -𝐼𝑅 𝑠 𝑅 𝑠ℎ
with I being the current (A), I0 being the reverse current (A), q being the elementary electronic charge, V corresponding to the external bias voltage, RS being the series resistance (Ω.cm²), n being the ideality factor, kB being the Boltzmann's constant, T being the absolute temperature in kelvin, and RSh being the shunt resistance (Ω.cm²).

Results

The electrical and optical properties of CuCrO2 and ZnO thin films synthesized on Corning glass as reference are presented in Table 2. The values for CuCrO2 films were obtained experimentally whereas the values for ZnO layers are extracted from previous experiments in our group [START_REF] Nguyen | Deposition of ZnO based thin films by atmospheric pressure spatial atomic layer deposition for application in solar cells[END_REF] and validated by the repetition of these experiments. As previous found [START_REF] Bottiglieri | Out of stoichiometry CuCrO2 films as a promising p-type TCO for transparent electronics[END_REF] , the at.% of Cu in the CuCrO2 films has an impact on the different properties:, an increase in Cu ratio initially shows a reduction of the electrical resistivity of the thin films, presenting a minimum for samples synthesized by an initial solution composition of 70%. Increasing further the Cu ratio makes resistivity increases abruptly by 1.5 orders of magnitude and an enhancement of carrier mobility. The band gap shows a monotonical decrease with increasing Cu content. The effect of the stoichiometry on the performance of the devices was probed by varying the Cu/(Cu+Cr) in the initial solution. The diodes will be defined as CuCrO2:X , where X represents the % of Cu in the initial solution from which the films have been obtained. The ZnO layers were deposited at 100 °C in all cases.

The XRD patterns of CuCrO2:X films are reported in Figure 1.a) and were compared with the ICDD reference of the delafossite rhombohedral CuCrO2 structure (ICDD 04-010-3330) and cubic Cu2O (ICDD 00-005-0667). These results confirm the presence of CuCrO2 thanks to the (012) and the (110) reflection at 2θ=36.4° and 2θ=62.4° associated to the CuCrO2 phase. For the two highest compositions i.e., X=70% and X=80%, the formation of the Cu2O is proved by the appearance of the reflection (200) at 2θ=42°. These results are in good agreement with our previous works [START_REF] Bottiglieri | Out of stoichiometry CuCrO2 films as a promising p-type TCO for transparent electronics[END_REF][START_REF] Bottiglieri | Optimized Stoichiometry for CuCrO2 Thin Films as Hole Transparent Layer in PBDD4T-2F:PC70BM Organic Solar Cells[END_REF] . A schematic diagram of the device structure is visible in Figure 1.b). The ohmic contact between the probes and the various layers that make up the device were confirmed by the linear characteristic of the Au/ITO/CuCrO2/Au and Au/ITO/ZnO/Au structures, Figure S1.

The effect of varying the CuCrO2 stoichiometry, X, over the electrical performances of these diodes is reported in Figure 1.c). The limited electrical properties of the integrated TCOs allowed us to consider the effective surface of the device that of the size of the used electrodes and a negligible lateral conductivity.

All the fabricated devices present a rectification ratio, with a value of Ion/Ioff (±2.5V) ≥ 1000, regardless the composition of CuCrO2 used. Furthermore, these measurements confirm the p-type conductivity of CuCrO2 synthesized by an initial solution of 50% and 60%, which was challenging to confirm by Hall Effect measurement, due to the moderate magnetic field in our system. This demonstrates the successful applicability of these thin films as p-type semiconductor for diode applications. The electrical noise found in the J-V characteristic of the CuCrO2:60% and CuCrO2:70% devices is attributed to the extremely low reverse bias current, in the order of pA, below the system detection limit. The best performances were obtained for CuCrO2:70% devices with a corresponding Ion/Ioff (±2.5V) around 10 5 . This is mainly attributed to the reduction of the current under reverse polarization.

The trend of Ion/Ioff ratio with the composition of the initial solution is confirmed by the statistical analysis of several devices deposited on different samples in the same deposition conditions, Figure 1.d), where a minimum of 3 diodes were tested. The reproducibility of these results obtained for the most performant device was also validated through the fabrication of 4 different samples using the same conditions, Figure S2. Despite the variability of the performances, the devices CuCrO2:70% always showed a rectification ratio greater than 10 4 , Figure S2, two orders of magnitude higher than similar devices reported previously in the literature [START_REF] Chiu | Fabrication of transparent CuCrO2:Mg/ZnO p-n junctions prepared by pulsed laser deposition on glass substrate[END_REF][START_REF] Narro-Ríos | Spray pyrolysis synthesis of a semi-transparent p-CuCrO2/n-ZnO heterojunction: Structural, optical, and electrical properties[END_REF] .

Based on these results, CuCrO2:70% was chosen to further improve the devices by optimizing the n-type ZnO layer. In particular, the deposition temperatures and thickness for ZnO was varied. Increasing the deposition temperature from 100 to 200 °C results in a reduction of the resistivity, through a simultaneous increase of the mobility and carrier density ( Table 2). The increase in the deposition temperature also leads to a reduction in the energy gap. Finally, the deposition temperature modifies the structural properties of the films, as visible in Figure 2.a). The ZnO films deposited at 100 °C show a poor crystallinity, while films deposited at 150 and 200 °C show an increasing crystallization and a texture change towards the (002) direction, according to ICDD 00-036-1451.

For a deeper insight into the effect of the various deposition parameters involved in this work, refer to our previous publications on ZnO [START_REF] Nguyen | Deposition of ZnO based thin films by atmospheric pressure spatial atomic layer deposition for application in solar cells[END_REF] . The effect of the ZnO deposition temperature on the characteristic of the diodes is reported in Figure 2.b). The highest rectification ratio is achieved for device where the ZnO film was deposited at 100°C. Furthermore, we can observe a shift of the origin of the curves, as visible in Figure 2.b). This can be justified by the presence of recombination centers at the interface. We observe that the origin of the J-V characteristic tends towards the zero-bias value, when increasing the deposition temperature of ZnO. This is coherent with the fact that a greater deposition temperature would reduce the presence of impurities i.e., recombination centers at the interface which may work as dipoles thus resulting in charge accumulation and the shift of the curves.

The effect of the thickness of the ZnO layer deposited at 100° C was also investigated, Figure S3. We used 160 ALD cycles to deposit a 30 nm thick ZnO film, and 320 ALD cycles for a 60 nm thick ZnO film, maintaining the other parameters constants. The obtained rectification ratio, for the thinner layer, around 4200, is lower than for the thicker ZnO film, due to a reduction of the forward current. This may be attributed to a greater presence of recombination centers for the thinner film, resulting in increased carrier recombination at the interface and finally limiting the current in the ON state. Hence, the best results were obtained for the combination of CuCrO2 synthesized by X=70% and a 60 nm thick ZnO film deposited at 100 °C, summarized as ITO/CuCrO2:70%/ZnO-100°C-320 cycles. The impact of the thickness of the CuCrO2 will be source of further studies. The structural, morphological, optical and compositional properties of the optimized architecture, ITO/CuCrO2:70%/ZnO-100°C-320 cycles were analysed. Raman spectroscopy was employed to probe the phonon modes of the ITO/CuCrO2:70% and ITO/CuCrO2:70%/ZnO structures, Figure 3.a).1) and 3.a).2), respectively. CuCrO2:70% presents modes at 99 cm -1 , 108 cm -1 , 149 cm -1 , 216 cm -1 , and 649 cm -1 . The Raman mode at 99 cm -1 is attributed to the Eu mode of the CuCrO2 phase, while the further modes are assigned to the Cu2O phase, which present more active Raman modes than the delafossite one [START_REF] Bottiglieri | Out of stoichiometry CuCrO2 films as a promising p-type TCO for transparent electronics[END_REF] . This demonstrates the deposition of a nanocomposite composed of Cu2O+CuCrO2, as expected from our previous results [START_REF] Bottiglieri | Out of stoichiometry CuCrO2 films as a promising p-type TCO for transparent electronics[END_REF] . The additional broad and badly formed Raman mode in the 500-600 cm -1 is attributed to the ITO substrate. The Raman spectrum for the complete device is reported in Figure 3.a).2). The additional Raman lines found at 90 cm -1 and 439 cm -1 are assigned to the E2 low and E2 high modes of the ZnO wurtzite structure, respectively.

GIXRD has been used to confirm these results. The pattern of the ITO substrate, Figure 3.b).1), is reported as comparison. We can observe in Figure 3.b).2 corresponding to ITO/CuCrO2:70% sample the peaks at 31.9° and 65,3° attributed to the (012) and the (001 ̅ 2) reflections of the delafossite; the remaining peaks are attributed to the ITO substrate. The GIX RD pattern of the optimized p-n junction is reported in Figure

3.b).3)

. Additional peaks at 31.7°, 36.2°, 56.6°, and 67.9° are attributed to the (100), ( 101), (110), and (112) reflections of the ZnO wurtzite phase respectively. The polycrystalline nature of this film is in good agreement with previous results obtained for the ZnO seed layers used to grow ZnO nanowires [START_REF] Cossuet | ZnO/CuCrO2 Core-Shell Nanowire Heterostructures for Self-Powered UV Photodetectors with Fast Response[END_REF] . SAED pattern of the optimized device, figure S4), confirmed the results obtained by XRD.

Cross-section TEM observations were employed to measure the thickness of the films, as shown in Figure 3.c). The device is composed of 30±5 nm of CuCrO2 film and 60±10 nm for ZnO.

The in-depth profile of the atomic content (C, Cu, Zn and O) of the optimized p-n junction, analyzed by XPS, is represented as a function of the etching time in Figure 3.d). The interface is found after around 900 s of sputtering. The signal of Cr2p3/2 orbital is not reported because it overlapped the one of Zn Auger, in the 580-590 eV range. One can observe a small region, around the interface, where both Zn and the Cu are present. However, we attributed this overlapping to the accuracy of the technique and the fact that our films are very thin, rather than inter-layer diffusion. Finally, this profile allows us to conclude that our layers are chemically stable and no interdiffusion occurs among them, thanks to the low deposition temperature used for the synthesis of ZnO. This is in agreement with the results obtained for the Cu0.66Cr1.33O2/ZnO junctions, where the authors demonstrated that even after annealing at 700 °C, the layer would not interdiffuse [START_REF] Afonso | Transparent p-Cu0.66Cr1.33O2/n-ZnO heterojunction prepared in a five-step scalable process[END_REF] . Furthermore, we can observe a clear accumulation of carbon contamination at the interface, which can be considered the responsible for the shift of our curve with respect to the zero-bias. The evolution of the spectra for the various elements as a function of the etching time is reported in Erreur ! Source du renvoi introuvable..

The transmittance spectra for each fabrication step of the device are reported in Figure 4.a). The average optical transmittance in the 400-800 nm range increases from around 60% for the ITO/CuCrO2:70% structure up to 75% for the finalized device. This increase suggests that the ZnO film works as an antireflective coating, mitigating the reflectivity of the CuCrO2. Similar values of transparency were obtained by Wang et al. [START_REF] Wang | Combustion Synthesis of p-Type Transparent Conducting CuCrO2+ x and Cu:CrOx Thin Films at 180 °C[END_REF] for ITO/CuCrO2+x/ZnO structure.

The J-V characteristic of the optimized device was fitted, and the results are reported in Figure 4.b). The turn-on voltage was obtained from the linear fit of the J-V characteristic in linear scale, Figure S4. The obtained values for the threshold voltage, the ideality factor η, the series resistance, and the shunt resistance were 0.85 V, 3.9, 850 Ω.cm -2 , and 350 MΩ.cm -2 , respectively. Figure 5 shows the energetic level of the different layers and the resulting band diagram for the optimized p-n junction, Figure 5.a) and Figure 5.b), respectively. The electronic affinity was obtained from the literature, with values around 4.7 eV 61 for ITO, 2.1 eV 54 for CuCrO2, 4.3 eV 62 for ZnO, and 5.1 eV [START_REF] Kumar | Perspectives and challenges for organic thin film transistors: Materials, devices, processes and applications[END_REF] for Au.

In the case of CuCrO2, we assume that these values were not significantly influenced by the variation in stoichiometry. For the n-type TCO, this value was previously used by Afonso et al. [START_REF] Afonso | Transparent p-Cu0.66Cr1.33O2/n-ZnO heterojunction prepared in a five-step scalable process[END_REF] for ZnO deposited at 150 °C by ALD, thus we consider it applicable in our case as well. These values indicate a type-II alignment between the CuCrO2 and ZnO.

The energy gap values were extracted from our previous works, as reported in Table 1. with values of 2.9 eV 57 and 3.4 eV [START_REF] Nguyen | Deposition of ZnO based thin films by atmospheric pressure spatial atomic layer deposition for application in solar cells[END_REF] for the CuCrO2 and ZnO, respectively. The position of the Fermi level for Cu2O+CuCrO2 was obtained in our previous work [START_REF] Bottiglieri | Out of stoichiometry CuCrO2 films as a promising p-type TCO for transparent electronics[END_REF] , assuming a similar valence band structure for CuCrO2:60%, and the CuCrO2:70%, with values around 70 meV, above the valence band maximum (VBM). This is in good agreement with the extremely high carrier density for the delafossite. Furthermore, the formation of a secondary phase can lead to the formation of quasi-Fermi levels between the VBM and the Fermi energy. Thus, the out of stoichiometry CuCrO2 is very likely to present a broadening of the bands with less localized states close to the VBM. For ZnO, the low crystallinity and the short-range order, as demonstrated by XRD and SAED, would imply a broadening of the band edges into tails of localized states.

The performance of our devices were compared with those in the literature for p-n junctions based on the same materials, Figure 6. Based on this comparison, we can assert that our optimized device presents the highest rectifying ratio ever reported, 3 orders of magnitude greater than what is present in the literature. Moreover, they are characterized by very high transparency, around 75% in the visible range, one of the highest for these devices. These findings highlight that our devices are excellent candidates for highlyperformant transparent p-n junctions.

Discussion

In this work, p-CuCrO2/n-ZnO diodes were fabricated and analysed. First, an optimization of the composition of the p-type oxide grown by AAMOCVD was carried on, while the ZnO top layer was always deposited at 100°C by AP-SALD. These devices are labelled CuCrO2:X, where X represent the cationic ratio i.e. Cu/(Cu+Cr) in the solution employed to synthesize the p-type semiconductors. From these results, Figure 1, we can observe that films with solution composition of 70% correspond to the best candidate, with a value of Ion/Ioff (±2.5V) around 10 5 . The greater performances of CuCrO2:70% can be explained through the simultaneous enhancement of the crystallization for the 70% film and the improvement of the transport properties. Indeed, if one supposes only a reduction of the energy gap with the out-stoichiometry, Table 2, one should expect that the CuCrO2:60% would present a greater rectification ratio than the 70%. However, this is not observed suggesting that other parameters play a more significant role over the performances of the device. As explained by Lim et al. [START_REF] Lim | Chemical spray pyrolysis deposition and characterization of p-type CuCr1-xMgxO2 transparent oxide semiconductor thin films[END_REF] , the increase of the reverse current implies the presence of current leakage paths through deep defects states at the interface, whose density would be reduced by a greater crystallinity of the films. Based on these considerations, it can be expected that the CuCrO2:70%, which possesses a greater crystallinity than the CuCrO2:60% film as proved by our previous work [START_REF] Bottiglieri | Out of stoichiometry CuCrO2 films as a promising p-type TCO for transparent electronics[END_REF] , presents a lower reverse current, i.e., greater rectification ratio than the CuCrO2:60%. The same applies when increasing the % of Cu from 70% to 80%, i.e. a degradation of the transport properties yields a lower performance of the diode. In our previous work [START_REF] Bottiglieri | Optimized Stoichiometry for CuCrO2 Thin Films as Hole Transparent Layer in PBDD4T-2F:PC70BM Organic Solar Cells[END_REF] , we demonstrated that the stoichiometry of the films results in a negligible effect over the roughness of the films, thus we exclude that the evolution of Ion/Ioff found for increasing cationic ratio would be related to a significant change in morphology. However, also the transport properties of the film, Table 1, play an important role in the final device performance, tuning, for instance, the depletion region width. Moreover, we cannot exclude the rise of the interband gap state through the formation of Cu2O for the nanocomposite films which occurs at 70% solution composition.

Based on these results, CuCrO2:70% was selected to further improve the devices by optimizing the n-type ZnO layer deposited by AP-SALD. In particular, the effect of deposition temperatures for ZnO over the performances of the diodes was analysed in Figure 2. The forward bias current exceeds the reverse bias current by two orders of magnitude for the three deposition temperatures. As mentioned before, a higher deposition temperature would lead to an increase in the film crystallinity and electrical conductivity. The increase in reverse current corresponds to the main cause of the deteriorated rectification ratio. While this may sound contradictory with the discussion above for CuCrO2, one has to take into account the possible different evolution of the interface at the different ZnO deposition temperatures. Indeed, Chiu et al. [START_REF] Chiu | Fabrication of transparent CuCrO2:Mg/ZnO p-n junctions prepared by pulsed laser deposition on glass substrate[END_REF] reported devices with inverted architecture, namely, ZnO/CuCrO2:Mg and observed that a greater deposition temperature for the top layer deposition and the large lattice mismatch of the used n-and p-type semiconductor may induce defects at the interface and at the grain boundaries resulting in an increasing leakage current. This will complicate the correlation between the properties of the top layer (ZnO in our case) and the diode performances. In our case, we can suppose that the poor crystallinity of the ZnO deposited at 100 °C may minimize the leakage paths through grain boundaries thus resulting in a limited reverse current, contrarily to what observed for diodes where ZnO was deposited at a temperature higher than 100 °C.

The greatest performances were obtained for the combination of CuCrO2 synthesized by X=70% and a 60 nm thick ZnO film deposited at 100 °C, summarized as ITO/CuCrO2:70%/ZnO-100°C-320 cycles. These heterojunctions were further characterized. GI-XRD and Raman spectroscopy demonstrated the deposition of a nanocomposite Cu2O+CuCrO2 and of a ZnO wurtzite structure. XPS profiling evidences no significant interdiffusion of the cations and the presence of carbon contamination at the interface, which can be explained through the exposure of CuCrO2 to open-air between the two deposition processes. Based on this we can forecast the amelioration of the performance through a greater cleaning of the interface before the deposition of the ZnO.

Two main parameters extrapolated by the fitting of the experimental curves are here discussed, the ideality factor and the threshold voltage.

The found ideality factor, 3.9, is coherent with previous reports of all oxides-based diodes, where the typical value is greater than 2 2,54,64 . Only recently, Narro et al. [START_REF] Narro-Ríos | Spray pyrolysis synthesis of a semi-transparent p-CuCrO2/n-ZnO heterojunction: Structural, optical, and electrical properties[END_REF] reported a similar junction with a value of η as low as 1.57. In our case, the value of η can indicated the presence of additional recombination processes in addition to the Shockley-Read-Hall recombination phenomena. It is our belief that the majority of these recombination center is located at the interface among the semiconductors. The formation of such defects at the interface is likely attributed to the presence of adventitious carbon at the surface of the p-CuCrO2, its deviation from stoichiometry and the appearance of the cuprous oxides in the lattice matrix. The latter may represent a further degree of crystalline disarrange. All these factors may result in the arise of intraband states, justifying the discrepancy with the ideal diode. However, the proper definition of their origin and energetic levels will be subject of further studies.

Similar hypotheses were proposed by Afonso et al. [START_REF] Afonso | Transparent p-Cu0.66Cr1.33O2/n-ZnO heterojunction prepared in a five-step scalable process[END_REF] , to explain the found value for ideality factor of 6.6, for diodes with a similar structure, Cu0.66Cr1.33O2/ZnO. The authors attributed their relatively high values to the formation of mid-gap impurity levels active as localized states induced by a high interface defect density or the chromium excess. The parasitic resistance values are influenced by different factors, such as the electrical properties of the thin films, the quality of the interfaces, and defects generated during fabrication. Thus, any speculation about these values may lead to improper conclusions. The fitted values suggest a great quality of the CuCrO2:70%/ZnO planar heterostructure obtained here. Nevertheless, it can be observed that the experimental characteristic does not pass through the origin, differently by the fitting curve. As explained above, this can be justified by the presence of defects at the interface, which may act as dipoles thus resulting in accumulation of the charges, resulting in a shift of the curves. This may also suggest that the junction may show a hysteresis in the J-V curves, acting as piezoelectric or ferro electric material, finally appealing for memory applications. Nevertheless, this study was considered for future analysis and it is has not been investigated by our group so far.

The threshold voltage should correspond to the difference in energy of the VBM of the p-type semiconductor and the conduction band minimum of the n-type one. In our case we estimated a value of ΔEc, around 2.2 eV, while we obtained a turn-on voltage, around 0.85 eV. This suggests the presence of interfacial states, similar to the results reported by Afonso et al. [START_REF] Afonso | Transparent p-Cu0.66Cr1.33O2/n-ZnO heterojunction prepared in a five-step scalable process[END_REF] . The authors explain that the presence of defects states at the interface can justify the lower voltage necessary to flatten the bands when compared to the energetic difference between the conduction bands. In our case, the presence of a high interface defect density can be explained by the formation of the Cu2O secondary phase, the Cu excess of the p-type TCO side, and the poor crystallinity of the ZnO. These factors will result in the broadening of the bands with the formation of midgap levels, allowing the carrier conduction even with a lower amount of energy. The presence of these intrabands levels can justify the high performances and the high ideality factor for our devices.

Our fabrication process presents various advantages.

i) First, we successfully fabricated our devices through relatively rapid and scalable methods. ii)

Second, we employed the lowest deposition temperature ever reported for this type of thin films (Tmax 350°C), without the use of vacuum techniques or additional post annealing treatments. iii) Furthermore, the results presented are achieved without the use of extrinsic dopant, for none of our layers. This represents an additional advantage since it makes our manufacturing process less sophisticated than the many reports previously reported. iv)

Finally, all these factors will contribute to the reduction of costs and time for the production of high-performance p-n planar heterojunctions, thus resulting an extremely appealing factor for the industrialization of such technology.

These results highlight the feasibility of the proposed oxides as promising semiconductors for transparent heterojunctions, revealing great performance of the devices as well as an auspicious route to fabricate them.

Conclusions

We reported high-performance diodes based on ZnO and on out of stoichiometry CuCrO2 fabricated by chemical deposition methods at low temperature and ambient pressure, without the requirement of any further post-deposition treatment. After a selection of various deposition parameters, the architecture was optimized, resulting in an ITO/CuCrO2:70%/ZnO. The diodes prepared in this work present the highest rectification ratio reported in the literature, with mean values around 10 5 . The reproducibility of these results was confirmed. These extremely high performances are attributed to the formation of intraband levels, due to the stoichiometry variation of the CuCrO2 phase and the poor crystallinity of n-type ZnO deposited at low temperature, 100 ºC. Moreover, these devices are characterized by very high transparency in the visible range, around 75%, due to the antireflective properties of the ZnO thin films. These encouraging results and the upscaling possibilities are extremely appealing for the industrialization of such transparent and oxidebased devices.

Figure 1 .

 1 Figure 1. a) XRD patterns of out of stoichiometry CuCrO2 thin films synthesized on glass by a value of X (solution concentration) of 1) 50%, 2) 60%, 3) 70% and 4) 80%. The CucrO2 phase is identified by the reflection (012) at 36.4° and the Cu2O by the reflection (200) at 42°. b) Schematic architecture of diodes with CuCrO2 as p-type TCOs, indicated as CuCrO2:X and ZnO as ntype. c) J-V characteristics in dark for the CuCrO2:X devices for ZnO deposited at 100°C. d) Box chart of the Ion/Ioff calculated from the J-V characteristics obtained by at least 3 diodes deposited in different samples. The percentiles are set to 95% whisker top, 75% box top, 25% box bottom, and 5% whisker bottom for each data set. The solid and empty squares represent the outliers and the mean, respectively.

Figure 2 .

 2 Figure 2. Effect of the deposition temperature of ZnO by AP-SALD a) XRD patterns of the ZnO layers deposited at 1) 100°C, 2) 150°C, and 3) 200°C, adapted by the Nguyen Ph.D. thesis 65 . b) Effect of the deposition temperature of ZnO over the J-V characteristics of the device when combined with CuCrO2:70%. The number of ALD cycles was adapted to obtain a 60 nm film, at each temperature

Figure 3 .

 3 Figure 3. Structural, morphological and optical properties of the optimized structure composed by CuCrO2:70% and polycrystalline ZnO. b) Raman spectra of 1) ITO/CuCrO2:70% and 2) p-n junction. b) GIXRD patterns of 1) ITO covered glass, 2) ITO/CuCrO2:70% and 3) ITO/CuCrO2:70%/ZnO-100°C-320 cycles. The legend in figure 3.a) is valid also in b). c) TEM cross section of the optimized architecture p-n junction. d) atomic content depth profile as a function of the etching time acquired by XPS for the same sample.

Figure 4 .

 4 Figure 4. a) Comparison between transmittance spectra of ITO, ITO/CuCrO2:70%, and ITO/CuCrO2:70%/ZnO. The spectrum of the glass substrate is reported for comparison. The inset shows the macroscopic aspect of the device, before the deposition of the gold contacts. b) Fitting of the ITO/CuCrO2:70%/ZnO device characteristics.

Figure 5 .

 5 Figure 5. a) Proposed energetic levels of each material prior the contact. The values were obtained by the references and Tauc plot. b) Band diagram for the p-n junction based on CuCrO2:70% and ZnO. Here, the interface states are evidenced.

Figure 6 .

 6 Figure 6. Rectification ratio, Ion/Ioff, as a function of the average transmittance in the visible for CuCrO2/ZnO based heterojunctions, as obtained by literature. Each work is labelled based on the deposition technique used for the CuCrO2 and ZnO synthesis

Table 1

 1 Summary of the productive steps reported in the literature for the fabrication of CuCrO2 and ZnO-based heterojunctions.

CuCrO 2 ZnO Structure Annealing Rectification ratio (ION/IOFF) Average transmittance in visible(%) Reference Growth technique Growth temperature (°C) Growth technique Growth temperature (°C)

	2.1 Device fabrication
	Out of stoichiometry CuCrO2 thin films were synthesized on borosilicate glass (Corning glass 1737) and
	ITO-covered glass (Delta technologies CG-51IN-S115) using AA-MOCVD. Films deposited on Corning
	glass 1737 were used as references, while the ones deposited on ITO were used for the fabrication of the
	devices. The initial solution was composed of chromium (III) acetylacetonate (CrC15H21O6 by Sigma
	Aldrich) and copper (II) acetylacetonate (CuC10H14O4 by Strem Chemicals) in ethanol, with a total molar
	concentration fixed at 10 mM. The Cu partial molar concentration in the solution i.e.
	Spin coating [𝐶𝑢(𝑎𝑐𝑎𝑐) 2 ] RT ([𝐶𝑢(𝑎𝑐𝑎𝑐) 2 ]+[𝐶𝑟(𝑎𝑐𝑎𝑐) 3 ]) coating Spin	RT	CuCrO2+x/ZnO	10 min TA 180°C	NR	>70	32
	DLI-MOCVD	450	ALD	150	Cu 0,66	Cr	1,33	O	2 /ZnO	TA 15 min 700°C	-4 to +4 13 V	50	54
	SP	500	SP	400	ZnO/CuCrO	2	/	107	55	55
	SP	450	LP-CVD	400	CuCr	0.93	Mg 0.07	O	2 /ZnO	/	10	75

Table 2

 2

	CUCRO2
	Cu/(Cu+Cr) in the solution (%)	ρ (Ω.cm)	µ (cm².V -1 .s -1 )	N (cm -3 )	Eg (eV)
	50	1	< 0.1	NR	3.2
	60	0.1	< 0.1	NR	3.05
	70	0.08	0.9	1 x 10 20	2.9
	80	1.2	1.1	8 x 10 19	2.6

Electrical and optical properties for out of stoichiometry CuCrO2 and ZnO films on glass. The information reported is the electrical resistivity (ρ), the carrier mobility (µ), charge carrier density (N), and energy gap (Eg) for the two materials deposited under the different conditions. In this table, 'NR' stands for not reliable corresponding to the experimental impossibility of measuring the transport properties of certain materials.

in these devices, however the obtained rectification ratio is extremely poor, around 13, achieved only after thermal annealing at high temperature, 700 °C, incompatible with the majority of glass substrates.

Acknowledgments

L. Bottiglieri acknowledges the French Ministry of Higher Education and Research for funding his PhD scholarship. This research has benefited from the characterization equipment of the Grenoble INP -CMTC platform supported by the Centre of Excellence of Multifunctional Architectured Materials ''CEMAM'' noANR-10-LABX-44-01 funded by the ''Investments for the Future'' Program. This work benefited from the facilities and expertise of the (OPE)N(RA characterization platform of the FMNT (FR 2542)) supported by CNRS, Grenoble INP and UGA. The authors would like to warmly acknowledge Laetitia Rapenne for the help on TEM observations and Hervé Roussel for the aid on the GI-XRD pattern acquisition. Agence Nationale de la Recherche (ANR) is acknowledged for financial support under contracts ANR-16-CE05-0021 (DESPATCH) and ANR-15-IDEX-02 (Eco-SESA).


Valérie Leroux
email: valerie.leroux@isab.fr

Loïc Sauvée
email: loic.sauvee@isab.fr

UN CADRE D'ANALYSE STRUCTURATIONNISTE DES RELATIONS PARTENARIALES

Keywords: évolution, individu, interaction, organisation, partenariat, relation, structuration, système social

L'objectif de cette communication est de proposer un cadre d'analyse de l'évolution des relations partenariales. Ce cadre d'analyse est centré sur les dimensions interactives au sein de la relation modélisée comme système social complexe.

Dans un premier temps nous proposons une revue de la littérature consacrée à ce sujet de la dynamique partenariale pour en dégager les principales caractéristiques. Nous distinguons ainsi deux courants majeurs. Le premier courant privilégie l'étude des facteurs explicatifs influençant la relation partenariale : son évolution apparaît ainsi conditionnée par l'existence d'éléments endogènes et/ou exogènes. Le second courant met l'accent sur la dimension systémique de la relation : celle-ci est alors vue comme ayant sa logique propre et son évolution peut être éclairée par une étude de la nature des forces à l'oeuvre.

Dans un second temps nous précisons les bases conceptuelles de notre cadre d'analyse, en relation avec ces travaux. Nous considérerons que la relation partenariale constitue un système social complexe, où les interactions entre individus, organisations et éléments contextuels sont à l'origine des modifications dans la structuration de la relation. Par nature non prédictive, cette évolution peut néanmoins être éclairée en considérant le processus par lequel les individus et les organisations construisent, par leurs interactions constantes, la structure et sont en retour modelés par elle. Pour ce faire, notre cadre d'analyse se compose de deux étapes complémentaires. La première étape fait référence aux éléments structurants du système partenarial : mode de coordination de la relation partenariale d'une part, relations individu/organisation d'autre part. Cette identification d'éléments structurants est à la base d'une définition de six formes archétypales de relations partenariales. Dans une seconde étape, nous proposons une grille de lecture des interactions fortes au sein du système partenarial. Ces interactions sont regroupées en familles de phénomènes liant entre eux les éléments de la structure à un triple niveau : inter-individuel, inter-organisationnel et en lien au contexte.

Dans un troisième temps nous appliquons ce cadre d'analyse à une relation partenariale entre un producteur agricole et un grossiste. Cette relation se déroule sur une période de douze années. De sa mise en place jusqu'à sa dissolution, elle passe par une suite d'évènements qui en modifie la structure. Le cadre d'analyse proposé permet de mieux comprendre son évolution. Il met notamment en évidence la dimension interactive forte du phénomène partenarial, son caractère mouvant, contingent et aléatoire, ainsi que l'importance des dimensions individuelles et contextuelles dans son devenir.

Introduction

Sous l'effet d'un développement multiforme des relations inter organisationnelles, les frontières de l'organisation se transforment et appellent à des redéfinitions régulières de leurs contours. Ces pratiques questionnent largement ces dernières années la communauté académique quant aux raisons d'être, aux performances ou au fonctionnement des relations partenariales. Notre objectif est de venir enrichir ces travaux en proposant un cadre d'analyse centré sur les dimensions interactives au sein de la relation modélisée comme un système social complexe. Après une analyse de la littérature organisée en deux pôles -les approches factorielles de la dynamique versus les approches processuelles -(1), nous précisons les bases conceptuelles de notre cadre d'analyse (2). A cet effet, nous définissons notre acception du système 'relation partenariale' et nous présentons un modèle d'analyse en deux étapes complémentaires. Tout d'abord nous caractérisons des états types de la relation. Ensuite, nous proposons de rendre compte de la dynamique de la relation par la prise en compte des interactions se déroulant en son sein à trois niveaux : individuel, organisationnel et environnemental. Au travers d'une étude de cas, nous illustrons alors ce cadre (3) et en discutons les implications (4).

1-Approches théoriques de la dynamique des relations partenariales

Deux grands courants traversent la littérature traitant de la dynamique des relations partenariales. Le premier courant, dans une perspective factorielle, rassemble les travaux qui identifient les différents traits caractérisants de la relation, lesquels influencent son développement (1-1). Le second courant concerne les recherches qui se focalisent sur le déroulement de la relation dans le temps et qui, au travers d'approches processuelles, proposent des modélisations linéaires, circulaires ou dialectiques de leur évolution (1-2).

1-1 Approche factorielle de la dynamique des relations partenariales A l'aide de coupes transversales de la relation partenariale à divers moments de son développement, nombre d'auteurs ont cherché à en identifier les facteurs explicatifs. Un large pan de contributions souligne l'influence de facteurs endogènes à la relation, qu'ils concernent les attributs des partenaires impliqués dans la relation ou la configuration même du partenariat.

(i) Diverses considérations relatives à la similarité ou dissemblance des profils en termes de taille des partenaires, d'assise financière, de détention d'actifs, de réputation, d'existence éventuelle de liens antérieurs, de proximité culturelle, de positionnements concurrentiels relatifs…, ont été relevés comme ayant une influence sur le degré de facilité de mise en oeuvre du partenariat et sur les risques qui y sont associés [START_REF] Hladik | R&D and international joint ventures[END_REF][START_REF] Doz | Technology partnership between larger and smaller firms[END_REF][START_REF] Fedor | Making sense of cultural factors in international alliances[END_REF]Harrigan,1988 ;[START_REF] Wilkhof | When the stories are different: the influence of corporate culture mismatches on interorganizational relations[END_REF].

(ii) L'objet de la relation apparaît comme un autre élément déterminant du choix de la configuration organisationnelle à retenir [START_REF] Dussauge | Anticiper les conséquences des alliances stratégiques[END_REF][START_REF] Teece | Competition, Co-operation and Innovation[END_REF][START_REF] Gulati | The architecture of cooperation: managing coordination costs and appropriation concerns in strategic alliances[END_REF][START_REF] Bidault | Stability and complexity of inter-firms cooperation[END_REF]. Sont ainsi mis en évidence les problématiques du type de formalisation de la relation (contractuelle et/ou capitalistique) et des choix de modalités de structuration -qu'il s'agisse des modes de résolution des conflits, de partage des responsabilités, de la mise en place de systèmes d'informations commun, des modes de communication - [START_REF] Singh | Precarious collaborations: business survival after partners shut down or form new partnerships[END_REF][START_REF] Gulati | Alliances and Networks[END_REF][START_REF] Kale | Value Creation and Success in Strategic Alliances: Alliancing Skills and the Role of Alliance Structure and Systems[END_REF]. D'autres travaux soulignent quant à eux la nécessité de prendre en compte l'influence de facteurs exogènes regroupés sous l'appellation d'environnement de la relation -sectoriel, légal, environnemental -qu'ils interviennent dans le choix des modalités contractuelles ou, au cours de la relation, dans la nécessité d'une 'co-évolution' entre le partenariat et son environnement [START_REF] Dussauge | Learning from competing partners: outcomes and durations of scale and link alliances in Europe, North America and Asia[END_REF]Gulati,1995 ;[START_REF] Das | The Dynamics of Alliance Conditions in the Alliance Development Process[END_REF][START_REF] Claro | The determinants of relational governance and performance: how to manage business relationships?[END_REF].

Au final, ces travaux offrent une cartographie des multiples facteurs influençant la dynamique de la relation. Le repérage de leurs différentes modalités d'expression conduit à suggérer, de manière normative, les conditions qui sont les plus à même de conduire au succès de la relation ou tout au moins d'en faciliter le fonctionnement. Il revient ainsi à la sphère managériale la double tâche de gérer l'ensemble de ces facteurs endogènes en adoptant les modalités les plus favorables et de positionner la relation en cohérence avec les facteurs exogènes.

1-2 Approches processuelles de la dynamique des relations partenariales

Les analyses de la dynamique des relations partenariales à partir d'approches processuelles cherchent à comprendre comment et pourquoi les relations évoluent comme elles le font. En adoptant une perspective historique, ces approches se focalisent sur les incidents, activités ou étapes qui se déroulent le temps de l'existence de la relation [START_REF] Van De Ven | Suggestions for studying strategy process: a research note[END_REF].

Une large partie des travaux s'inscrit dans une démarche d'analyse de l'évolution globale -ou macroscopique-de la relation. Un premier courant s'appuie sur les théories du cycle de vie pour expliquer une dynamique d'ensemble linéaire de la relation [START_REF] Forrest | Strategic alliances between large and small research intensive organizations: experiences in the biotechnology industry[END_REF][START_REF] Kanter | Collaborative Advantage: The Art of Alliances[END_REF]. La relation naît, se développe puis meurt selon une logique endogène infaillible et totalement prédictible. Le second courant adopte les développements théoriques évolutionnistes en soulignant la nécessaire adaptation du partenariat à son environnement (Koza et Lewin,1998 ;Zollo et al., 1998). Au déterminisme endogène se substitue un déterminisme exogène.

Beaucoup plus rares sont les travaux cherchant à rendre compte de la dynamique de la relation dans son fonctionnement au quotidien. [START_REF] Ring | Developmental Processes of Cooperative Interorganisational Relationships[END_REF][START_REF] Doz | The Evolution of Cooperation in Strategic Alliances: Initial Conditions or Learning Processes?[END_REF] proposent une représentation de la dynamique des relations partenariales au travers Des contributions plus récentes proposent des analyses de la dynamique des relations partenariales en termes dialectiques (Das et Teng, 2000 ;[START_REF] Rond | On the Dialectics of Strategic Alliances[END_REF] [START_REF] Boddy | Implementing collaboration between organizations: an empirical study of supply chain partnering[END_REF] proposent une lecture de la dynamique partenariale à partir d'une approche constructiviste [START_REF] Giddens | La constitution de la société[END_REF][START_REF] Pettigrew | Context and action in the transformation of the firm[END_REF][START_REF] Pozzebon | The Influence of a Structurationist View on Strategic Management Research[END_REF]). Ils expliquent la dynamique de la relation par les interactions entre les acteurs et sept facteurs contextuels. Ces derniers facteurs apparaissent comme à la fois structurant de l'action humaine et structurés par cette dernière. Ces acteurs montrent ainsi que la dynamique des relations consiste largement en un processus émergent. Pour autant, la compréhension du déroulement des interactions entre les différentes composantes du système reste encore largement à construire. L'objet de cette communication est de contribuer à éclairer cette problématique.

2-La

2-1 La relation partenariale : une approche par la structuration

Les approches factorielles et la majeure partie des approches processuelles sont sous tendues par une acception de la relation partenariale tantôt comme système fermé tantôt comme système ouvert. Elles considèrent les relations comme des structures aux attributs bien identifiables, sous contrôle d'une équipe managériale et/ou sous dépendance de leur environnement. Les travaux les plus récents relevant d'une approche processuelle dialectique ou contextuelle font émerger une autre conceptualisation de la relation en insistant sur la nature complexe des relations partenariales. En référence à la théorie de la structuration de [START_REF] Giddens | La constitution de la société[END_REF], nous proposons de considérer les relations partenariales comme des systèmes sociaux produits et reproduits au travers des interactions des individus. Ce faisant, nous considérons que l'action et la structure se construisent mutuellement par récursivité et que l'attention doit être portée sur le processus de structuration de la relation partenariale, c' est-àdire sur les interactions. Rompant avec l'approche de la relation partenariale comme système fermé, il s'agit de considérer la nature ontologique complexe de ce système en tant qu'exprimant des propriétés d'auto-organisation, d'émergence et d'hétérogénéité [START_REF] Mathews | Why study the complexity sciences in the social sciences?[END_REF][START_REF] Anderson | Introduction to the Special Issue: applications of complexity theory to organization science[END_REF]. Il en découle, en terme de dynamique, des trajectoires non linéaires imprédictibles. L'étude en dynamique des relations partenariales suppose la prise en compte simultanée des éléments structurants de la relation et de la façon dont ses éléments interagissent. Par l'intermédiaire des individus, les différents sous-systèmes -organisations partenaires, groupe partenarial -vont interagir sans qu'il soit possible a priori d'en connaître le sens, la fréquence ou les résultats. Aucune hypothèse n'est émise a priori (i) sur la consistance des différents systèmes de la relation pour son développement et (ii) sur sa performance. Ainsi, une relation partenariale peut très bien perdurer malgré des divergences entre les partenaires ou en dépit de l'absence des résultats attendus [START_REF] Inkpen | Why do some strategic alliances persist beyond their useful life ?[END_REF]. A partir de ces présupposés, nous discutons des implications en terme de dynamique partenariale (2-2-2). La première dimension rend compte de la nécessaire coordination que les partenaires doivent mettre en place en vue d'atteindre leurs objectifs communs et qui s'exprime dans les dispositifs de gestion qui sont développés [START_REF] Mintzberg | The structuring of organization[END_REF]. Ces dispositifs correspondent aux procédures d'échanges d'information, de prises de décision, de modalités de partage des coûts, risques, bénéfices, etc. qui sont élaborés par les individus au fil de leurs interactions et qui constituent en même temps le support -habilitant et contraignant -de leurs interactions futures. Dans le flot de leurs échanges, les individus amenderont ces dispositifs, en créeront de nouveaux. Le produit et le support de cette négociation peuvent être caractérisés par un degré de formalisation variable le long d'un continuum [START_REF] Kast | Organization and management: a systems approach[END_REF]. De manière pratique, nous distinguons deux modalités :

2-2-1 La relation partenariale : éléments structurants

-une formalisation élevée : le pilotage de la relation s'appuie sur des supports juridiques (contrats) voire économiques (prise de participation financière dans une entité commune) explicites et sur des procédures codifiées. Dès lors, le degré d'intégration des décisions entre les partenaires sera fort : échanges d'information, procédures écrites de prise de décision, prise en compte d'aléas éventuels. En cas de conflit, ces éléments contractuels formalisés constituent une première source de références permettant d'arbitrer les différends.

-une formalisation faible : dans ce cas, aucun support juridique ou financier, aucune procédure ne vient structurer un pilotage commun. Le contact entre les partenaires peut éventuellement aller jusqu'à s'appuyer sur un comité informel rassemblant les individus impliqués dans la gestion de la relation au quotidien. Plus généralement, les relations entre les individus impliqués s'opèrent sur la base de contrats psychologiques et de confiance [START_REF] Granovetter | Economic action and social structure: the problem of embeddedness[END_REF][START_REF] Das | Trust, Control and Risk in Strategic Alliances: An Integrated Framework[END_REF].

Dans notre approche, la présence ou l'absence de structure formelle de pilotage ne préjuge en rien de la qualité de la relation. Il est même probable, dans la mesure où il est impossible de spécifier formellement tous les cas de figure auxquels la relation sera confrontée, que les processus informels soient incontournables. La seconde dimension s'intéresse au degré de contrôle qu'exercent les organisations partenaires sur la relation, en particulier au travers du niveau d'autonomie qu'elles accordent respectivement à leurs membres impliqués dans la relation partenariale [START_REF] Mintzberg | The structuring of organization[END_REF][START_REF] Romelaer | Rencontres et organisation[END_REF]. Deux modalités seront retenues :

-une autonomie forte : les individus en charge du management et de l'opérationnel de la [START_REF] Berger | The social construction of reality[END_REF]. Sous certaines conditions, des relations de confiance peuvent s'établir entre les individus parties prenantes de la relation. Elles constituent alors des contrats psychologiques informels entre les acteurs qui peuvent contribuer à préserver le devenir de la relation [START_REF] Argyris | Understanding organizational behaviour[END_REF], voire pour certains cas peuvent se substituer aux contrats légaux plus formels [START_REF] Dyer | The Relational View: Cooperative Strategy and Sources of Inter organizational Competitive Advantage[END_REF]. Il peut ainsi s'agir d'un mécanisme alternatif de résolution de conflit. Dès lors, tout changement dans les individus a pour effet de dé-initialiser les contrats psychologiques qui avaient cours.

Les interactions entre l'individu et son organisation

Ces interactions rappellent que le contexte dans lequel les échanges se développent est un cadre professionnel. L'individu est lié à l'organisation de manière formelle -au travers notamment de son contrat de travail -mais également de manière psychologique [START_REF] Rousseau | The contracts of individuals and organizations[END_REF]. La position qu'il occupe dans la hiérarchie, le rôle qu'il assume, [START_REF] Koenig | L'organisation dans une perspective interactionniste[END_REF][START_REF] Weick | The social psychology of organizing 2 nd edition[END_REF][START_REF] Weick | Sensemaking in Organizations[END_REF]. Cette représentation résulte largement elle aussi d'une co-construction mentale plus ou moins achevée des organisations en la personne de leur dirigeant, ce qui influe sur le devenir de la relation partenariale.

Les interactions avec l'environnement sur chacun des éléments de la relation partenariale Pour chacun de ces différents niveaux d'interaction, nous suggérons dans le tableau 2 la nature des tensions sous-jacentes et proposons des illustrations de l'impact de ces interactions sur la structuration globale de la relation partenariale. 3-1 L'étude de cas : perspective de la recherche et méthodologie Cette étude de cas longitudinale s'appuie sur les recommandations de [START_REF] Yin | Case Study Research: Design and Methods[END_REF], [START_REF] Huberman | Analyse des données qualitatives[END_REF], [START_REF] Dubois | Systematic combining: an abductive approach to case research[END_REF]. La démarche adoptée se situe dans une perspective abductive : l'étude de cas est perçue comme «un vecteur de généralisation analytique» (Yin, 1994 :31), où une théorie proposée a priori sert de cadre analytique pour comparer des Par ailleurs, la divergence de stratégie entre les partenaires concernant les investissements en traçabilité est patent, A souhaitant aller plus loin dans ce domaine.

-1999

Un autre phénomène contextuel d'importance survient en 1998 : l'apparition des premières 'filières qualité' mises en place par les grands distributeurs. Ceux-ci cherchent à développer des relations directes avec les fournisseurs, sans passer par un intermédiaire grossiste. Cette volonté s'explique par plusieurs facteurs : limiter les coûts, s'assurer une exclusivité de l'approvisionnement et permettre un meilleur contrôle des conditions de production. Le développement des volumes, encouragé par B, prend plusieurs formes : tentative de production au Portugal de manière à désaisonnaliser la production, extension de la gamme de légumes. Les échecs sont essentiellement supportés par A, et les risques sont jugés comme étant inégalement répartis entre les deux partenaires. L'arrivée d'un nouvel interlocuteur b3 permet de renouer un contact et de relancer la coopération. Les contacts interpersonnels sont établis et permettent à la relation partenariale, en dépit des difficultés, de trouver un second souffle.

-2000

Le contact entre les deux organisations cherche à créer de nouvelles conditions dans leurs

-2002

Cette période marque la fin de la relation partenariale. Les partenaires étant liés par un contrat de fourniture pour encore deux ans, les échanges se maintiennent sur cette période en s'estompant progressivement. La commercialisation de certains légumes est arrêtée.

Simultanément à l'arrêt de la relation, A développe son propre réseau commercial, tandis que B établit des contacts avec de nouveaux fournisseurs (noté F). L'analyse conduite au travers de l'étude longitudinale d'un partenariat entre un producteur agricole et un grossiste permet selon nous de valider l'intérêt de ce type d'approche. Elle met notamment en évidence le caractère dual de la structure vue comme processus résultant à la fois de tensions positives et/ou négatives entre les éléments structurants, mais ceci dans un cadre organisationnel -plus ou moins formalisé-déjà existant.

Placer le regard au niveau de cette construction sans cesse renouvelée de l'espace de structuration peut permettre d'améliorer la compréhension du devenir émergent des relations partenariales.

  d'approches circulaires et offrent, selon nous, deux contributions majeures. Tout d'abord la place accordée aux individus -principalement la sphère managériale-et à leurs interactions est explicitement identifiée comme l'un des moteurs fondamentaux. En particulier, la présence concomitante de processus formels et informels entre les acteurs lors du déroulement de la relation est énoncée. Les travaux de Doz soulignent quant à eux la nécessité de prendre en compte la dimension contextuelle dans laquelle s'insère la relation, qu'il s'agisse des conditions initiales ou d'évènements externes tout au long de sa vie, ce qui implique des réajustements de la configuration initiale. La dynamique de la relation se traduit en fait par une recherche d'équilibration permanente. Dans ces travaux, le passage d'une étape à la suivante s'opère sur la base d'une appréciation portée par les acteurs sur l'efficience de la relation et l'équité. L'idée sous jacente commune à ces approches est que la relation perdure et se développe parce qu'elle atteint des niveaux de performance suffisants ; dans le même temps cette notion de performance et son évaluation ne sont pas clairement spécifiées.

  . Divers couples de forces en opposition sont identifiés. Das et Teng repèrent principalement des tensions internes : coopération/compétition, flexibilité/rigidité, long terme/court terme. De Rond et Bouchikhi élargissent le modèle et soulignent l'influence d'autres forces antagonistes dans le déroulement de la relation : planification et émergence, confiance et méfiance, expansion et contraction, contrôle et autonomie. En terme de dynamique, Das et Teng estiment que lorsque l'une des forces domine, la relation se trouve en situation d'instabilité préfigurant des changements majeurs de configuration voire une dissolution. Dans une approche normative là encore, ils considèrent qu'il revient aux partenaires de gérer ces tensions pour positionner la relation en situation d'équilibre dynamique et lui permettre ainsi d'atteindre ses objectifs. De Rond et Bouchikhi plaident au contraire pour une approche où l'instabilité, née de ce jeu permanent des forces entre elles, est considérée comme un processus naturel et donc sans connotation négative sur la performance de la relation. La dynamique est alors faite d'une succession non intentionnelle de pics et de vallées sans progression prédéterminée vers un état final. Dans une approche comparable à celle de de Rond et Bouchikhi,

  relation partenariale comme système social complexe : fondements conceptuels et cadre d'analyse de la dynamique Nous souscrivons à une acception du concept de relation partenariale comme système social complexe, où les notions de structuration et de phénomènes d'interactions entre ces éléments occupent une place centrale (2-1). Nous présentons alors le cadre d'analyse permettant d'opérationnaliser notre approche : matrice de la relation partenariale et repérage des états types de relation partenariale d'une part, grille de lecture des interactions fortes et de la structuration de la relation d'autre part (2-2).

  Dans le cadre de cette communication, nous proposons d'opérationnaliser notre approche par une démarche en deux temps : tout d'abord en caractérisant structurellement la relation partenariale par divers états types, puis en expliquant la dynamique de la relation par le passage d'un état à un autre sous l'influence des interactions entre ses diverses composantes. 2-2 Matrice d'états de la relation partenariale et grille de lecture de la dynamique Il convient dans un premier temps de s'interroger sur les éléments constitutifs de la relation partenariale permettant de la caractériser à un instant donné. Deux éléments dans la relation partenariale entendue comme système sont pris en compte : le degré de coordination interne d'une part et le degré d'autonomie des individus en charge de la relation vis-à-vis des partenaires d'autre part (2-2-1). Dans un deuxième temps, nous nous intéressons aux interactions fortes au sein du système 'relation partenariale' et de sa relation avec le contexte.

  Les logiques fondamentales de coordination / contrôle auxquelles sont soumis les partenaires sont opérationnalisées au travers de deux dimensions : d'une part le degré de coordination de la relation et d'autre part le degré d'autonomie des individus vis-à-vis de leurs organisations respectives. Ces deux dimensions et leurs modalités sont abordées successivement.

  relation disposent d'une forte délégation dans leur prise de décision ou leur management, -une autonomie faible ou intégration : des liens étroits existent entre les individus impliqués dans la relation partenariale et l'ensemble de l'organisation dont ils font partie ; les échanges d'informations sont nombreux, les décisions concertées. Ce lien est étudié pour chacun des deux partenaires pris indépendamment l'un de l'autre, ce qui conduit à trois cas de figure possibles : autonomie de l'individu «i» dans l'organisation A et autonomie dans B ; intégration dans A et intégration dans B ; autonomie dans A et intégration dans B (ou vice versa). Sur ces bases, nous proposons une matrice d'états types de la relation partenariale (tableau 1) qui distingue des formes discrètes de la relation, représentant en quelque sorte des 'sauts qualitatifs'. Nous faisons l'hypothèse que ces cas types se différencient par leurs propriétés adaptatives/réactives aux interactions internes et externes (par exemple la capacité à s'adapter à des chocs externes comme une évolution de la concurrence, une hausse du marché), et par leurs propriétés de résistance à des tensions internes (une démission d'un individu, un conflit entre directions etc..). L'approche dynamique consistera alors à repérer les passages d'une forme discrète à une autre, sur la base d'une typologie commune et transversale. Tableau 1 La matrice d'états types de la relation partenariale (notée RP) Lien entre l'individu (a ou b) et son organisation (A ou B) 'états types de la relation partenariale identifie ainsi au final six cas.

  l'invite à certains comportements, par ailleurs attendus des autres participants avec lesquels il est en contact. Ainsi les actions qu'un individu peut être amené à prendre dans le cadre de son rôle organisationnel ne coïncident pas nécessairement avec les liens interpersonnels qu'il a pu développer. Par ailleurs, son indépendance lui permet de dépasser le cadre codifié de ses actions. Son appartenance à d'autres systèmes sociaux où les règles et références sont particulières -par exemple une corporation professionnelle -, ses expériences antérieures, ses valeurs personnelles, contribuent à façonner des attentes individuelles qui peuvent être en désaccord avec les projets que lui propose son organisation.Les interactions entre les deux organisations prises dans leur ensembleCe niveau d'interaction fait référence aux phénomènes de convergence ou de divergence dans les stratégies des partenaires, leurs préférences, leurs intérêts ou leurs pratiques(Adams et Goldsmith, 1999). L'origine de ce phénomène est le plus souvent liée au rapport de pouvoir (taille respective des organisations, position par rapport au marché final, accès à certaines informations etc…), à la complémentarité et à la spécificité des actifs engagés dans la relation, mais aussi aux influences réciproques qui s'exercent entre deux organisations dès lors qu'elles sont fréquemment en contact (mimétisme stratégique, influence réciproque des dirigeants, émergence et construction progressive d'intérêts stratégiques communs). Il faut noter également l'importance de la représentation que chaque organisation se fait de son partenaire, et d'une manière plus générale de son environnement stratégique

(

  individus et organisations) Sans exclusive, ces facteurs environnementaux peuvent avoir des origines très variées et traditionnellement regroupées sous le vocable de 'macro environnement'. Il s'agit de tous les phénomènes externes à la relation en ce sens qu'ils influent sur elle sans qu'en retour la relation puisse immédiatement agir sur eux (éventuellement d'une manière marginale ou en effet de feed back à moyen terme). Il peut s'agir de facteurs des environnements marchands (évolution des prix, des volumes, des standards de qualité, mais également évolution du marché de l'emploi et son influence sur les individus), institutionnels (aspects réglementaires), technologiques (exemple de l'impact des nouvelles technologies de l'information), stratégiques (évolution des comportements de clients ou de fournisseurs extérieurs à la relation partenariale).

  du travail ; valeurs des systèmes sociaux dont l'individu est membre Opportunités et menaces ; stratégies et pouvoir des acteurs (clients et fournisseurs) La pression concurrentielle s'intensifie pour un des partenaires qui souhaite alors contrôler au plus près la relation. Etat type 2 vers état type 4 3 -Application à une étude de cas : la relation partenariale entre un producteur agricole et un grossiste Le cadre d'analyse est appliqué à une relation partenariale ayant duré douze années entre un producteur agricole et un grossiste. Dans un premier temps nous détaillons la perspective de recherche retenue et la méthodologie employée pour cette étude de cas (3-1). Puis, selon un découpage chronologique en grandes périodes, nous relatons les principaux évènements de cette relation partenariale (3-2). Enfin nous effectuons une lecture des interactions au sein de cette relation et nous en explicitons les implications sur la structuration de la relation (3-3).

  figure 1 pour l'organisation générale de la relation partenariale)Le contexte de l'apparition de la relation partenarialeProducteur céréalier du Nord de la France, l'entreprise A décide, à la fin des années 80, de se diversifier dans la production de légumes de plein champ dans une région propice sur le plan climatique à ce type d'activité, le Sud Ouest. L'évolution des marchés céréaliers (diminution des prix de soutien, concurrence mondiale) est à l'origine de cette volonté de diversification.

  relations. A la demande de A, un service commercial ad hoc est créé par B. B s'engage également à une transparence des marges sur les transactions effectuées. Un troisième point montre un désaccord entre les partenaires : la volonté par A de réaliser directement la facturation aux clients distributeurs (noté C), tout en conservant l'acte commercial aux mains de B. Ce désaccord marque le point de rupture, qui est effective à la mi-2000. L'entreprise B considère en effet que cette pratique d'une facturation directe conduit de fait à ne considérer son activité que comme une simple activité de courtage. Le conflit d'intérêt est patent, alors même que les volumes commercialisés sont élevés et que le marché est jugé comme étant favorable. Un autre évènement va aggraver la situation : le commercial de B est engagé par A, précipitant ainsi la relation vers un conflit ouvert.

Figure 1

 1 Figure 1Le système de la relation partenariale entre A et B

  En parallèle, une forte délégation est octroyée aux opérationnels et aux individus en charge du management de la relation. action collective à laquelle ils participent et vont produire des règles et des normes permettant leur action[START_REF] Crozier | Instabilities of Strategic Alliances: an Internal Tensions Perspective[END_REF]. Ils vont ainsi créer, reproduire ou amender les règles sur lesquelles ils s'appuient ou les ressources qu'ils contrôlent. Ce faisant, la relation partenariale peut s'institutionnaliser, c' est-à-dire passer d'une transaction instrumentale à une relation sociale infusée de normes et de valeurs qui permettent que la relation soit reproduite et perpétuée au delà de sa création

	Cas Relation partenariale de gré à gré. La relation partenariale est ici gérée d'individus à
	individus. Les contrats psychologiques et la confiance constituent l'essentiel des fondements
	de la relation. On note l'absence conjointe de procédure formalisée et d'implication au niveau
	stratégique.
	Cas	Relation partenariale de sous traitance. Dans ce cas l'un des partenaires dispose
	d'une autonomie forte et l'autre non. Cette dimension asymétrique de la relation se combine à
	une formalisation élevée de la gestion de l'activité.
	Détaillons chacun d'entre eux et précisons, à titre illustratif, certaines caractéristiques
	distinctives.

Cas

Relation partenariale à cadrage opérationnel. Le fonctionnement de la relation est codifié et assure aux partenaires des modalités de prise de décision ou de gestion de l'activité dans une large part standardisées.

Cas

Relation partenariale de subordination. Des relations informelles lient des individus au degré d'autonomie, vis à vis de leurs organisations, asymétriques. Cette dimension asymétrique se combine à une formalisation faible de la relation, avec l'importance de la dimension inter-individuelle. Cas Relation partenariale à double cadrage. Il s'agit de l'état où les degrés de structuration et de contrôle par les partenaires sont les plus importants. En effet d'un côté l'intégration des individus dans leurs organisations respectives est forte et de l'autre la formalisation de la relation est importante. Cas Relation partenariale d'ajustement fonctionnel. La relation partenariale implique au plus haut point chacun des partenaires tout en conservant un mode de fonctionnement principalement informel.

Abordons maintenant la question des interactions qui se déroulent dans le cadre de ces relations partenariales.

2-2-2 Interactions dans le système 'relation partenariale'

Quatre familles d'interactions entre les différents sous systèmes de la relation partenariale sont identifiées : interactions entre individus, entre individus et organisations, entre organisations, entre l'environnement et la relation partenariale.

Les interactions entre les individus a et b parties prenantes de la relation

Cet axe renvoie à l'ensemble des échanges professionnels et interpersonnels qui vont se dérouler au cours de la relation. Dans leurs interactions, les individus vont expérimenter des jeux de pouvoir par la maîtrise différenciée de ressources, vont contribuer à élaborer un sens partagé de l'