Hung-Ling Chen

Andrea Cattoni

Romaric De Lépinau

Alexandre W Walker

Oliver Höhn

David Lackner

Gerald Siefer

Marco Faustini

Nicolas Vandamme

Julie Goffard

Oliver Hoehn

Benoît Behaghel

Christophe Dupuis

Nathalie Bardou

Frank Dimroth

Stéphane Collin
email: stephane.collin@c2n.upsaclay.fr

A 19.9%-efficient ultrathin solar cell based on a 205-nm-thick GaAs absorber and a silver nanostructured back mirror

published or not. The documents may come

Introduction

The efficiency of single-junction solar cells has improved consistently over time for both crystalline silicon (c-Si) and thin-film (CIGS, CdTe, GaAs) technologies, and contributed to the cost decrease and widespread development of photovoltaic devices. To date, solar cells made of c-Si reach 26.7% photoconversion efficiency using 165 µm-thick Si wafers [START_REF] Yoshikawa | Silicon heterojunction solar cell with interdigitated back contacts for a photoconversion efficiency over 26%[END_REF]. With high optical absorption and radiative efficiency, GaAs approaches the Shockley-Queisser limit [START_REF] Shockley | Detailed Balance Limit of Efficiency of p-n Junction Solar Cells[END_REF] and reached a record efficiency of 29.1% with 1-2µm-thick single-junction solar cells (3,[START_REF] Green | Solar cell efficiency tables (Version 53)[END_REF]. On the other hand, theoretical light-trapping models suggest that the solar cell thickness can be reduced by more than one order of magnitude while preserving state-of-the-art short-circuit currents [START_REF] Green | Lambertian light trapping in textured solar cells and light-emitting diodes: analytical solutions[END_REF][START_REF] Yablonovitch | Statistical ray optics[END_REF]. Such a thickness reduction improves the industrial throughput and saves scarce materials (e.g. tellurium in CdTe, indium in CIGS and III-V). It also helps improve the performance of solar cells. For a given density of defects, non-radiative bulk recombination decreases with the thickness, allowing for the use of materials with a reduced diffusion length. For space applications, ultrathin GaAs cells show increased tolerance to high-energy particle bombardment [START_REF] Hirst | Intrinsic radiation tolerance of ultra-thin GaAs solar cells[END_REF].

Overall, thinning the absorber has a beneficial effect on both charge carrier collection and open-circuit voltage. The best solar cell would be an ultrathin solar cell if maximal absorption can be maintained through efficient light trapping.

Different light trapping strategies have been proposed and successfully employed to compensate for the short-circuit current drop due to incomplete absorption in ultrathin layers (8 9,10). Disordered nanotextures are a conventional approach and allowed 8.6% efficiency with only 830nm-thick silicon layers [START_REF] Depauw | Sunlight-thin nanophotonic monocrystalline silicon solar cells[END_REF]. Front surface nanotexturing with inverted pyramid arrays coupled with a highly reflective back mirror were optimized for ultrathin silicon solar cells [START_REF] Branham | 15.7% Efficient 10-µm-Thick Crystalline Silicon Solar Cells Using Periodic Nanostructures[END_REF][START_REF] Gaucher | Ultrathin Epitaxial Silicon Solar Cells with Inverted Nanopyramid Arrays for Efficient Light Trapping[END_REF][START_REF] Wang | Absorption Enhancement in Ultrathin Crystalline Silicon Solar Cells with Antireflection and Light-Trapping Nanocone Gratings[END_REF] and led to 15.4% efficiency with 10µmthick c-Si layers [START_REF] Branham | 15.7% Efficient 10-µm-Thick Crystalline Silicon Solar Cells Using Periodic Nanostructures[END_REF]. However, efficiencies exceeding 20% were only achieved with c-Si solar cells thicker than 40µm [START_REF] Kapur | A Manufacturable, Non-Plated, Non-Ag Metallization Based 20.44% Efficient, 243cm2 Area[END_REF]. Nanostructured back mirrors were used to increase long-wavelength absorption in III-V/Si tandem solar cells [START_REF] Cariou | III-V-on-silicon solar cells reaching 33% photoconversion efficiency in two-terminal configuration[END_REF], and a numerical study has shown broadband absorption capabilities in 150nm-thick CIGS solar cells [START_REF] Goffard | Light Trapping in Ultrathin CIGS Solar Cells with Nanostructured Back Mirrors[END_REF]. Dielectric nanoparticles were also successfully introduced at the rear side of CIGS solar cells with no significant impact on FF and Voc, leading to 12.3% efficiency with a thickness of 460nm [START_REF] Van Lare | Light Coupling and Trapping in Ultrathin Cu(In,Ga)Se2 Solar Cells Using Dielectric Scattering Patterns[END_REF]. On the contrary, a-Si:H deposited on textured substrate shows improved absorption [START_REF] Söderström | Photocurrent increase in ni-p thin film silicon solar cells by guided mode excitation via grating coupler[END_REF][START_REF] Zhu | Nanodome Solar Cells with Efficient Light Management and Self-Cleaning[END_REF] but low electrical performances. Overall, the best light trapping designs tend to avoid texturation of the absorber.

Ultrathin GaAs solar cells can be considered as a model system to investigate the potential of lighttrapping for high-efficiency ultrathin solar cells. Metal nanoparticles [START_REF] Liu | Surface plasmon enhanced GaAs thin film solar cells[END_REF][START_REF] Nakayama | Plasmonic nanoparticle enhanced light absorption in GaAs solar cells[END_REF] and nanogrids [START_REF] Massiot | Metal Nanogrid for Broadband Multiresonant Light-Harvesting in Ultrathin GaAs Layers[END_REF] can improve absorption via plasmonic resonances [START_REF] Atwater | Plasmonics for improved photovoltaic devices[END_REF], but the beneficial effect is usually compensated by metal absorption losses at short wavelengths. The integration of a highly reflective back mirror is a first requirement for efficient light trapping [START_REF] Vandamme | Ultrathin GaAs Solar Cells With a Silver Back Mirror[END_REF], and it can boost the open-circuit voltage (Voc) through the photon recycling effect [START_REF] Miller | Strong Internal and External Luminescence as Solar Cells Approach the Shockley-Queisser Limit[END_REF]27,[START_REF] Walker | Impact of Photon Recycling on GaAs Solar Cell Designs[END_REF]. Yang et al. have used a rough scattering Au back-mirror to further enhance light trapping. They achieved 19.1% efficiency with 300nm-thick solar cells [START_REF] Yang | Ultra-thin GaAs single-junction solar cells integrated with a reflective back scattering layer[END_REF]. In contrast, Lee et al. combined front-side periodic TiO2 nanostructures with a flat back reflector and reached 16.2% efficiency in 200nm-thick GaAs solar cells [START_REF] Lee | High Performance Ultrathin GaAs Solar Cells Enabled with Heterogeneously Integrated Dielectric Periodic Nanostructures[END_REF]. State-of-the-art ultrathin GaAs solar cells are listed in Table 1. Overall, previous achievements make use of light scattering and diffraction and lie below numerical predictions for double-pass absorption.

In this work, we propose a light trapping strategy based on multi-resonant absorption. We demonstrate a certified efficiency of 19.9% with a 205nm-thick GaAs solar cell using planar active layers and a silver nanostructured back mirror with a periodical pattern. It is fabricated using a low-cost and scalable technique based on direct embossing of TiO2 sol-gel derived film. The back mirror induces multiple overlapping resonances that provide efficient light trapping over a broad spectral range. The short-circuit current exceeds significantly an ideal double-pass absorption model while preserving FF and Voc. A detailed analysis of the optical and electrical properties of the device shows the path to reach 25% conversion efficiency using the same light-trapping scheme. [START_REF] Vandamme | Ultrathin GaAs Solar Cells With a Silver Back Mirror[END_REF]. The exact geometry of the grating is optimized with numerical computations based on the rigorous coupled-wave analysis (RCWA) method [START_REF] Lalanne | Reticolo software for grating analysis[END_REF][START_REF] Lalanne | Computation of the near-field pattern with the coupled-wave method for transverse magnetic polarization[END_REF][START_REF] Lalanne | Highly improved convergence of the coupled-wave method for TM polarization[END_REF][START_REF] Li | New formulation of the Fourier modal method for crossed surface-relief gratings[END_REF] (details in Methods): Ag square nanostructure width d=420 nm (60% of the period), grating height h=120 nm.

The epitaxial stacks were grown by Metalorganic Vapor Phase Epitaxy (MOVPE) on a n-type GaAs substrate in the following sequence: n+GaAs top contact, n-AlInP window layer, 205 nm GaAs absorber, p-AlGaAs back surface field (BSF) and p+GaAs rear contact. Note that the final solar cell structure is reversed compared to the growth order. A detailed description of the III-V semiconductor layers is given in the Supplementary Table 1. Figure 1(a) shows a schematic of solar cell fabrication sequences. Details about the cell fabrication process are reported in the Methods.

Step 1 begins with the fabrication of 5×5

µm² Ti/Au localized ohmic contacts on p+GaAs every 50 µm. Uncovered area of p+GaAs is wetchemically etched to reduce parasitic optical absorption. In step 2, large-area nanostructures are formed using soft nanoimprint lithography (NIL). TiO2 sol-gel was spin-coated on the sample surface and printed using a PDMS mold. Figure 1(b) shows a SEM image of the nanoimprinted two-dimensional periodic TiO2 grating. A silver mirror is deposited to cover conformally both ohmic contacts and TiO2 nanopatterns (step 3). Then, the mirror side of the sample is bonded to a glass host substrate using a flexible polymer, and the GaAs substrate is removed by chemical etching (step 4).

Performances of ultrathin GaAs solar cells

The best cell was measured by Fraunhofer ISE calibration laboratory under standard test conditions (AM1.5G, 1000 W/m², 25°C, see Supplementary Figures 10-18

Light trapping analysis

To illustrate our light trapping designs, three different solar cells were fabricated out of the same epitaxially grown semiconductor stack: solar cells (A) as-grown on GaAs substrate with a single-layer ARC (70 nm-thick SiNx), (B) with a flat silver mirror and DLARC, and (C) with a nanostructured silver mirror and DLARC. Their current-voltage characteristics are compared in the Supplementary Figure 1.

Their EQE are measured using a Fourier Transform Photocurrent Spectroscopy (FTPS) setup calibrated with a silicon reference cell, and a microscope objective is used to focus light onto a small spot (diameter:

a few 100 µm) between the wires of the front contacts in order to avoid shading. The results are plotted in

2 𝑘 !,! ℎ ! ! + 𝜑 = 2𝜋𝑞 (1)
where kz,i=2πni/λ is the z-component wavevector at normal incidence in layer i (thickness hi and refractive index ni), λ is the wavelength and the integer q defines the FP order. The phase change 𝜑 induced by reflection at the top and bottom interfaces is evaluated from the complex Fresnel coefficients. The result is shown in Figure 3(e) (green dashed lines) for the two FP resonances α1 and α2 found at short wavelengths.

They correspond to FP orders q=6 and q=7 (labeled FP6 and FP7, respectively). The low contrast of these resonance peaks is due to the high absorption and efficient DLARC in this wavelength range.

In the long wavelength range (λ>600 nm), the absorption peaks exhibit a strong period dependence and are attributed to guided-mode resonances. The grating scatters light into diffracted waves of orders (m1,m2) defined by their in-plane wavevectors:

𝑘 // (! ! ,! ! ) = 𝑘 // (!!) + 𝑚 ! !! ! 𝑒 ! + 𝑚 ! !! ! 𝑒 ! (2)

Loss analysis and path toward 25% efficiency

In this section, we analyze the performance of the ultrathin solar cell with a nanostructured mirror and discuss the possibility to achieve even higher efficiency. Figure 4(a) summarizes the detailed loss analysis for Jsc, FF and Voc: our experimental results are shown in bold and top values correspond to radiative limits. The Jsc reference of 31.9 mA/cm² is calculated for 205 nm-thick GaAs using an approximate lambertian light-trapping model [START_REF] Green | Lambertian light trapping in textured solar cells and light-emitting diodes: analytical solutions[END_REF][START_REF] Yablonovitch | Statistical ray optics[END_REF]. We measured Jsc=24.6 mA/cm² and the highest EQE without front contact shading (5-6% of the total area) results in Jsc=25.1 mA/cm², close to the numerical calculation of 25.6 mA/cm² for the optimized TiO2/Ag back mirror. Small discrepancy is due to the actual shape of fabricated structures. Parasitic optical losses contain absorption in the window layer (dJ=1.3 mA/cm²), in the BSF (dJ=1.2 mA/cm²), in the Ag mirror (dJ=2.7 mA/cm²) and due to reflection (dJ=1.1 mA/cm²). Parasitic absorption in the metallic reflector can be avoided through a combination of high-index-contrast gratings with all-dielectric or hybrid dielectric/metallic mirrors [START_REF] Barugkin | Diffuse reflectors for improving light management in solar cells: a review and outlook[END_REF][START_REF] Fu | Approaching conversion limit with all-dielectric solar cell reflectors[END_REF]. The stack of semiconductor heterostructures needs further optimization to reduce the thickness of the AlInP and AlGaAs layers and improve collection of photogenerated carriers in these layers. The shape of the nanostructured back mirror could be also optimized to improve light-trapping. For instance, replacing squares by L-shape or blazed nanostructures breaks a plane of symmetry and should increase the number of resonance modes by a factor of two. Overall, assuming half of the optical losses are recovered leads to a short-circuit current over 28 mA/cm².

To analyze the electronic characteristics of the solar cells, 1-sun JV curves are fitted using a two-diode model with a fixed Jsc and diode idealities of 1 and 2 [START_REF] Suckow | diode fit[END_REF]. An example of fit is given in Figure 4(b),

showing the absolute values of 𝐽 𝑉 -𝐽 !" in logarithmic scale and different components of the two-diode model. The fitted parameters are: J01=2.8×10 -17 mA/cm², J02=4.3×10 -8 mA/cm², Rp=2.4×10 3 ohm cm² and Rs=0.8 ohm cm². This procedure is repeated for every solar cell of different surface areas of 1×1, 2×2 and 3×3 mm². The Voc decreases with the cell size and is correlated with an increased dark current density J02. The size-dependence of the recombination current is observed in GaAs [START_REF] Ochoa | 3-D modeling of perimeter recombination in GaAs diodes and its influence on concentrator solar cells[END_REF] and can be recovered through edge passivation using S-based chemicals [START_REF] Sheldon | GaAs Passivation with Trioctylphosphine Sulfide for Enhanced Solar Cell Efficiency and Durability[END_REF]. In Figure 4(c), we plot the J02 values as a function of the perimeter-to-surface ratio (P/A). The linear trend allows to decompose J02 into a surface area component J02,A and a perimeter component J02,P (41):

𝐽 !" = 𝐽 !",! + 𝐽 !",! ! ! (3)
For large-area solar cells, edge recombination is suppressed. J02 reaches J02,A=8.7×10 -9 mA/cm².and results in an increase of Voc up to 1.045 V and FF up to 0.826. The corresponding JV characteristics are plotted in Figure 4(d). Further improvements of the fill factor are expected with improved parallel and series resistances: FF=0.84 for Rp=10 6 ohm cm² and FF=0.857 for Rs=0. The visible shunt conductance under illumination may be due to native oxides across the p-n junction at the edge or degradation from process steps after the mesa edges are revealed by chemical etching. The series resistance can be further optimized with GeAu alloys [START_REF] Shen | Recent developments in ohmic contacts for III-V compound semiconductors[END_REF] and a smaller spacing of contact grids. To achieve even higher FF, the dark current density J02 should be lowered down to about 10 -9 mA/cm² (3).

Regarding Voc, we calculate the radiative limit using the detailed balance principle applied for 205 nmthick GaAs solar cells [START_REF] Miller | Strong Internal and External Luminescence as Solar Cells Approach the Shockley-Queisser Limit[END_REF][START_REF] Sandhu | Detailed balance analysis of nanophotonic solar cells[END_REF][START_REF] Xu | The generalized Shockley-Queisser limit for nanostructured solar cells[END_REF] (see Supplementary Note 5). The calculated limit efficiency (25°C, illumination AM1.5G spectrum) is 𝜂 = 24.6% for the cell with a flat mirror (Jsc=23.4 mA/cm², Voc=1.172 V, FF=0.896) and 𝜂 = 32.3% for the cell with lambertian light-trapping (Jsc=31.9 mA/cm², Voc=1.132 V, FF=0.893). We note that the Voc radiative limit is reduced by 40 meV for lambertian light-trapping as compared to a flat mirror because of enhanced radiative emission (photonic bandgap narrowing, BGN). However, most of the Voc loss in our devices originates from nonradiative recombination (see Figure 4(d)). The choice of high doping is favorable for lateral conductivity and a high built-in potential in ultrathin absorber, but p-type GaAs is known for the bandgap narrowing (BGN) effect which lowers the bandgap by about 26 meV at the doping concentration of 10 18 cm -3 (45).

To achieve high Voc, reducing non-radiative loss and maintaining efficient photon recycling are of upmost important. Based on the above discussion, an efficiency of 25% (Jsc=28 mA/cm², Voc=1.05 V, FF=0.85) appears as a realistic target for 205 nm-thick GaAs solar cells with an optimized design. and3). (d) JV characteristics of the record solar cell and the fit. Efficiency can be increased by successive improvements of fitted parameters (see the main text): saturation current density J02 (yellow green curve), shunt resistance (blue curve) and series resistance (black curve). Inset shows a zoom around the maximum power point.

Conclusion

In conclusion, we have conceived and fabricated ultrathin GaAs solar cells with a TiO2/Ag nanostructured back mirror using soft nanoimprint lithography. We achieved a certified efficiency of 19.9% under AM1.5G illumination (Jsc=24.64 mA/cm², Voc=1.022 V, FF=0.792). The EQE exhibits a strong absorption enhancement in the 600-900 nm wavelength range, in agreement with numerical calculations. Broadband absorption is the result of multiple overlapping resonances induced by the nanostructured mirror, identified as Fabry-Perot and guided-mode resonances. We have revealed the origin of optical and electrical losses and proposed routes for further optimizations so that 200 nm-thick ultrathin GaAs solar cell with 25% efficiency appears as a realistic short-term target. These results constitute a very significant improvement over previous experimental achievements and numerical predictions of realistic devices and demonstrate that broadband light trapping is compatible with high performances. These results can find direct applications in flexible, lightweight, and radiation-resistant photovoltaic system for space applications. For large-scale photovoltaics, applying a similar architecture to thin-film solar cells made of CIGS and CdTe opens up promising perspectives for material savings and throughput improvements. In this context, this approach based on nanoimprinting sol-gel could represent a game changer for low cost and large-scale fabrication of nanostructured mirrors compatible with industrial constraints.

Methods

Semiconductor layer stack. The III-V semiconductor layers were grown by Metalorganic Vapor Phase Epitaxy (MOVPE) at the Fraunhofer Institute for Solar Energy Systems (ISE). The layers with target thickness and doping level are given in Supplementary Table 1. Zn and Si were used as p-type and n-type dopants, respectively. The growth was conducted on a n-type GaAs(100) substrate, consisting of buffer GaAs, AlGaAs etch stop (used for the substrate removal), n+GaAs/GaInAs contact layers, n-AlInP window, 205 nm GaAs homojunction as the main absorber, p-AlGaAs back surface field (BSF) and p+GaAs contact layer. Wide-bandgap AlGaAs and AlInP alloys are used to passivate the GaAs surface and act as minority carrier blocking layer to reduce surface recombination losses. The fabrication process of devices was performed at the Centre for Nanoscience and Nanotechnology (C2N) and is sketched in Figure 1.

Localized back contacts fabrication. Localized p-type back contacts consist of 5×5 µm 2 squares regularly spaced with a period of 50 µm in both x-and y-direction on the layer surface defined using photolithography (coverage: 1% of the total surface). After deoxidation of p+GaAs in a dilute HCl solution, localized Ti/Au (20/200 nm) was fabricated using electron-beam assisted evaporation and liftoff. Uncovered area of p+GaAs was etched in a mixture of citric acid at 1 g/L and hydrogen peroxide (30%) with a 5:1 volume ratio. Etching is naturally stopped at top of the AlGaAs layer (BSF).

Nanostructured TiO 2 /Ag mirror fabrication. After localized back contacts fabrication a dielectric mirror was fabricated by direct embossing of TiO 2 derived sol-gel film followed by a silver deposition.

For the embossing of the TiO 2 sol-gel derived film, we used Degassing Assisted Patterning (DAP) [START_REF] Luo | Degassing-assisted patterning of cell culture surfaces[END_REF], a modified version of Soft Nanoimprint Lithography that allows for a rapid embossing of sol-gel derived films [START_REF] Dalstein | Nanoimprinted, Submicrometric, MOF-Based 2D Photonic Structures: Toward Easy Selective Vapors Sensing by a Smartphone Camera[END_REF]. The technique makes use of a degassed polydimethylsiloxane (PDMS) based stamp to improve the resolution and rapidity of the embossing of sol-gel derived films. Unlike other Nanoimprint techniques, replication by DAP is driven by the inner underpressure of the stamp, and therefore does not require the use of an embossing machine. Because no external pressure is applied, DAP induces no longrange pattern deformations, limits short-range deformations, and is thus suitable for large surface area patterning. The PDMS based stamp is first degassed in a dessicator for 10 min. TiO 2 sol-gel hybrid is spin-coated on the AlGaAs surface (BSF) and the PDMS based stamp is then molded (in air). Eventual macroscopic air bubbles surrounding defects and/or localized around the localized back contacts are removed within few seconds through the diffusion of air in the degassed PDMS based stamp. In the same way, the air trapped in the stamp protrusion is aspired inside the stamp and replaced by the TiO 2 sol-gel.

The degassed stamp also quickly removes the ethanol and the water expelled during the sol-gel transition (gelation), hydrolysis and condensation occurring when the sol-gel is stabilized at 110°C for 5 min on a hot-plate before the demolding of the stamp. Subsequently, the top surface of the sample (coated with TiO 2 nanostructures) was protected with a photoresist mask, opening only the area of the localized ohmic contacts. The residual of nanoimprinted TiO 2 above the localized contacts was etched by dipping shortly the sample in a dilute HF solution. Ag (200 nm) was then deposited by electron-beam assisted evaporation using a rotating stage with a 10° tilt to the surface normal to ensure conformal deposition of Ag on both localized ohmic contacts and TiO 2 nanostructures. A TiO 2 /Ag nanostructured back mirror was thus obtained and acted at the same time as the back electrode.

Bonding and substrate removal. The Ag mirror-side of the sample was bonded to a glass host substrate using ormostamp (flexible hybrid inorganic/organic polymer), which was reticulated under UV light for following a procedure developed in reference [START_REF] Wang | Fabrication of Surfaces with Extremely High Contact Angle Hysteresis from Polyelectrolyte Multilayer[END_REF].

Hard-PDMS/PDMS stamp fabrication: the silicon master is replicated into a composite hard-PDMS/PDMS stamp by using the procedure similar to the one proposed in reference [START_REF] Odom | Improved pattern transfer in soft lithography using composite stamps[END_REF]. The hard-PDMS/PDMS stamp is finally treated with Trimethylsilyl chloride (TMCS) silanes by chemical vapor deposition method [START_REF] Cattoni | Soft UV-NIL at 20 nm scale using flexible bi-layer stamp casted on HSQ master mold[END_REF].

Sol-gel initial solutions: absolute ethanol was purchased from Normapur, inorganic precursor TiCl 4 and F127 Pluronic (EO106-PO70-EO106) were purchased from Aldrich. Dense TiO2 thin films were prepared by spin coating solutions composed of TiCl 4 :F127:H 2 O:EtOH with respective molar ratio of 1:0.0001:10:50. Final solution was obtained by dissolving the precursors TiCl 4 in ethanol and water followed by the addiction of a small amount of F127 (to improve the wettability).

Optical simulations and refractive indices. Optical simulations have been performed with the rigorous coupled wave analysis (RCWA) method [START_REF] Lalanne | Reticolo software for grating analysis[END_REF][START_REF] Lalanne | Computation of the near-field pattern with the coupled-wave method for transverse magnetic polarization[END_REF][START_REF] Lalanne | Highly improved convergence of the coupled-wave method for TM polarization[END_REF][START_REF] Li | New formulation of the Fourier modal method for crossed surface-relief gratings[END_REF]. We choose the x-z plane as the plane of incidence and consider impinging plane waves linearly polarized. We call transverse electric (TE) incident polarization for electric field perpendicular to the incidence plane (along the y-axis), and transverse magnetic (TM) incident polarization for magnetic field perpendicular to the incidence plane. We calculate the absorption in each layer with 20 Fourier order, and the calculation is done for each wavelength. The refractive indices used for optical simulation of ultrathin GaAs solar cells are plotted in Supplementary Optimization of the optical design. The geometry of ultrathin GaAs solar cells has been optimized by maximizing the theoretical short-circuit current J th . For the double-layer anti-reflection coating (DLARC) on ultrathin GaAs solar cells with a flat mirror, the best value is obtained for MgF 2 /Ta 2 O 5 layers of thickness 78/48 nm. For ultrathin GaAs solar cells with a nanostructured Ag back mirror, we use the same DLARC and determine the optimal geometry as: grating height h=120 nm, period p=700 nm, and silver square nanostructures of width 420 nm (60% of the period).

Figure 1 (

 1 c) shows a cross-section SEM image of a similar sample fabricated until this step, showing the TiO2/Ag back mirror. Subsequently, Ni/Ge/Au front contact grids are fabricated on n+GaAs, and solar cells of 1×1, 2×2 and 3×3 mm² sizes are protected with photolithography mask in the wet-chemical etching for the mesa. MgF2/Ta2O5 78/48 nm double layers anti-reflection coating (DLARC) is deposited (step 5).

Figure 1 :

 1 Figure 1: Fabrication process of ultrathin GaAs solar cells with a nanostructured back mirror. (a) Sketches of the main fabrication steps. (b) SEM image of nano-imprinted TiO2 periodic structures before Ag mirror deposition, the inset shows the cross-section shape of the TiO2. (c) SEM cross-section view after removing the GaAs substrate, showing the Ag nanostructured back mirror.

  ). The current-voltage (JV) characteristics and external quantum efficiency (EQE) are shown in Figure2. We achieve a record efficiency of 19.9% using only 205 nm-thick GaAs absorber, with JV parameters: Jsc=24.64 mA/cm², Voc=1.022 V and FF=79.2%. The solar cell area is 4.02 mm², which includes front contact grids (~5.5% shading of the total surface) in the calculation of the current density and conversion efficiency. The curve 1-R (R: specular reflectance) plotted in Figure2(b)represents the total absorption above 700 nm. Its spectral features exhibit multi-resonant absorption and match perfectly with the EQE in the long-wavelength range (700-900 nm). The integral over all photon energies of the EQE with the AM1.5G solar spectrum results in an equivalent Jsc=24.39 mA/cm², close to the direct measurement under 1 sun illumination.

Figure 2 :

 2 Figure 2: Best ultrathin solar cell based on a 205nm-thick GaAs absorber and a nanostructured Ag mirror. (a) IV characteristics and (b) external quantum efficiency of the 19.9%-efficient solar cell with an aperture area of 4.02 mm² measured at the Fraunhofer ISE calibration laboratory under standard condition (AM1.5G 1000 W/m², 25°C). The black curve 1-R (R: specular reflectance) plotted in (b) exhibits multiresonant features in agreement with the EQE.

Figure 3 (

 3 Figure 3(a) and compared to absorption calculations shown in Figure 3(b). The RCWA method is used to compute the electromagnetic fields and absorption spectra in each layer of the solar cell structures. The simulations are in good agreement with EQE measurements (see also Supplementary Note 4) and show a similar trend for the different structures. The light-trapping effect is clearly evidenced in the long wavelength range (λ>600 nm). The flat silver mirror results in double-pass absorption with an increase of the short-circuit current of ΔJsc=4.4 mA/cm 2 . With the nanostructured back mirror, numerous overlapping resonances contribute to further absorption enhancement and result in an additional ΔJsc=4.5 mA/cm 2 . Theoretical short-circuit current densities Jth sum up to Jth=25.6 mA/cm² for structure C. The measured EQE exhibits less pronounced resonances due to fabrication imperfections, but similar average absorption. The cross-section maps of the generation rates displayed in Figure 3(c) for 1 µm-thick GaAs solar cells and structures A, B and C illustrate the spectacular increase of the density of photogenerated carriers, as a result of efficient light trapping in a 205 nm-thick GaAs layer.

  where 𝑘 // (!!) is the in-plane wavevector of incident waves and (m1,m2) are integers. The additional inplane momentum induced by the grating allows coupling through ether transverse-electric (TE) or transverse-magnetic (TM) guided waves propagating in the solar cells. The approximate resonance wavelengths are calculated using a model of planar waveguide[START_REF] Yeh | Optical waves in layered media[END_REF], taking into account the quasiperiodic boundary condition for the in-plane component (Equation (2)). The coupling between guided modes is not taken into account in this simple model. Nevertheless, it allows to fit and to identify the main resonances: β1 and β3 are TE guided modes coupled to the diffracted orders (±1, ±1), β2 and β5 are TM guided modes coupled to the diffracted orders (±1, 0), β4 is TE guided mode coupled to the diffracted orders (±1, 0), γ1 and γ2 are TE and TM guided modes coupled to the diffracted orders (±2,0), respectively.The corresponding dispersion curves are plotted in Figure3(e) and agree with rigorous numerical calculations. They exhibit different slopes related to the different diffracted orders. The origin and characteristics of both Fabry-Perot and guided-mode resonances are further confirmed by their angular dependence, and by the number and position of nodes and anti-nodes in the field distributions (see Supplementary Note 1 and 3 and Supplementary Figures5 and 7). Overall, the integrated absorption maintains a high short-circuit current (Jth>25 mA/cm² up to 45°, Jth>23.5 mA/cm² up to 60°) through overlaps of multiple resonances (Figure3(f)).

Figure 3 :

 3 Figure 3: Optical analysis of the ultrathin GaAs solar cells. (a) EQE measurement for 3 different types of solar cells: (A) as-grown on a GaAs substrate, (B) with a flat Ag back mirror and (C) with a nanostructured Ag back mirror. 1-R (solar cells C) is also plotted (black curve). (b) Calculation of optical absorption in 205 nm-thick GaAs for the same structures. Structure A: as-grown with a single-layer ARC (dashed) or with the same design as B (reverse order without back mirror). Structure C: detailed absorption in each III-V layer (AlInP sum up to dJ=1.3mA/cm 2 , AlGaAs: dJ=1.2mA/cm 2 ). (c) Crosssection maps of the generation rate in 1µm-thick GaAs solar cells (DLARC, as-grown), and structures A, B and C (see Supplementary 2). (d) A schematic of the different types of resonances. (e) Dispersion diagram of 1-R as a function of the illumination wavelength and the period of the diffraction grating. Dashed curves are resonance wavelengths calculated with analytical models (see text for details). (f) Polar plot of the calculated Jsc as a function of the incident angle in 205 nm-thick GaAs (structure C).

Figure 4 :

 4 Figure 4: Current-voltage characteristics and loss analysis. (a) Detailed loss analysis for Jsc, FF and Voc. The different colors represent the different origins of losses that fill the gap between measurements (bold) and the radiative limit for 205 nm GaAs absorber (top values). Intermediate values in red appear as a realistic short-term target that corresponds to a conversion efficiency of 25%. (b) Typical JV curve under 1 sun illumination shifted with Jsc in log scale (red dot: J-Jsc) and fit with a two-diode model (blue curve). Different components of the model are shown in dashed lines. (c) Correlation of the J02 saturation current density with the perimeter-to-surface ratio P/A. Dashed line: linear fit of J 02 values extracted from square solar cells of width 3mm (3 devices), 2mm (3 devices) and 1mm (9 devices) (see also Supplementary Figs 2 and 3). (d) JV characteristics of the record solar cell and the fit. Efficiency can be increased by successive improvements of fitted parameters (see the main text): saturation current density J02 (yellow green curve), shunt resistance (blue curve) and series resistance (black curve). Inset shows a zoom around the maximum power point.

Figure 4 .

 4 Figure 4. The refractive indices are taken from reference (51) for Ta 2 O 5 , from reference (52) for MgF 2 and Al 0.42 Ga 0.58 As, and from reference[START_REF] Schubert | Isotropic dielectric functions of highly disordered AlxGa1-xInP lattice matched to GaAs[END_REF] for Al 0.51 In 0.49 P. We use refractive indices of high-purity GaAs[START_REF] Palik | Handbook of Optical Constants of Solids[END_REF][START_REF] Sturge | Optical Absorption of Gallium Arsenide between 0.6 and 2.75 eV[END_REF], and we fit the near bandgap extinction coefficients with cubic spline and extend the data in the sub-bandgap region with an exponential Urbach tail of energy width 10 meV for n-GaAs and 20 meV for p-GaAs. Larger band tail is attributed for p-GaAs to simulate the higher sub-bandgap absorption. The refractive index of Ag is taken from the measurement published recently in reference[START_REF] Jiang | Realistic Silver Optical Constants for Plasmonics[END_REF] to account for realistic absorption loss in Ag. TiO2 prepared from sol-gel with our process has typical refractive indices about 1.9 at 500 nm and is kept constant over the whole spectrum.

Table 1 :

 1 Comparison of record thin and ultrathin single-junction GaAs solar cell performances with different absorber thicknesses. Jsc values are normalized by the result of an ideal double-pass absorption model (𝐴 = 1 -𝑒 !!!" ) to highlight the light trapping capability.

		Absorber	J sc	Jsc/double-	Voc (V)	FF	Efficiency
		thickness t	(mA/cm²)	pass			(%)
		(nm)		absorption
	Kayes et al. (3,4) ≥1000	29.68	0.94	1.122	0.865	29.1
	Yang et al. (29)	300	24.5	0.94	1.000	0.778	19.1
	Lee et al. (30)	200	21.96	0.94	0.942	0.78	16.2
	This work	205	24.64	1.05	1.022	0.792	19.9
	2. Design and fabrication of ultrathin GaAs solar cells
	Ultrathin GaAs solar cells require light trapping structures to compensate for the decreased absorber
	volume. The rationale of the solar cell design is as follows. III-V active layers are kept flat to avoid

Description of the silicon master, PDMS based stamp and sol-gel derived film.

  20 minutes. The GaAs substrate was etched in a NH 4 OH:H 2 O 2 :H 2 O (1:4:15) solution and the AlGaAs etch stop was removed in HF:H 2 O (1:20). After this step, the III-V layer stack order was inversed. Silicon master fabrication: the silicon master mold was fabricated by electron beam lithography carried out at 100 keV (Vistec EBPG5000+) using positive-tone PMMA resist (495PMMA A -solids: 7% in Anisole) and anisotropic reactive ion etching based on SF 6 /CHF 3 gasses. The Silicon master was treated with

	1H,1H,2H,2H-perfluorooctyltriethoxysilane (POTS) by chemical vapor deposition (CVD) method,
	Front contacts and anti-reflection coating. The front contacts with grid spacing of 600 or 800 µm were
	fabricated using the similar steps as localized back contacts. They consist of multilayers of
	Ni/Au/Ge/Au/Ni/Au (4/10/60/110/10/100 nm) with no post thermal annealing to avoid degradation of the

Ag mirror as well as the ultrathin GaAs absorber. Uncovered area of n-GaAs and n-Ga 0.87 In 0.13 As were etched in a mixture of citric acid at 1 g/L and hydrogen peroxide (30%) with a 5:1 volume ratio. The final solar cells of 1×1, 2×2 and 3×3 mm² were delimited with photolithography mask and mesa etching in dilute HCl (removing AlInP) and in H 3 PO 4 :H 2 O 2 :H 2 O (3:1:40) (removing GaAs). MgF 2 /Ta 2 O 5 (78/48 nm) double-layer anti-reflection coating (DLARC) was deposited using electron-beam assisted evaporation.

Acknowledgements

The authors acknowledge fruitful discussions with Jean-François Guillemoles, electromagnetic simulation support from Philippe Lalanne, Jean-Paul Hugonin and Christophe Sauvan, and financial support through the French ANR project NANOCELL (grant no. ANR-15-CE05-0026) and the French Renatech network.

Data availability. The data that support the plots within this paper and other findings of this study are available from the corresponding author upon reasonable request.

Author contributions

HLC carried out most of the fabrication steps for the solar cell experiments at C2N and performed optical modeling and results analysis. AW, OH, DL and FD designed the optimized GaAs solar cell layer structure, DL was writing the recipe for the epitaxy growth and GS evaluated characterization results in the Fraunhofer ISE CalLab. HLC, AC, RDL, MF, NV, JG, BB, CD, and NB developed and optimized the fabrication process. AC and MF specifically developed the nanoimprint process of TiO2 sol-gel films. NV contributed to the design and modeling of the devices. AC and SC developed the concept of ultrathin solar cells with a nanostructured back mirror and supervised the project. HLC and SC wrote the manuscript. All co-authors participated in the discussions and improvements of the manuscript.

Competing interests

The authors declare no competing interests.

Additional information

Supplementary information is available for this paper.

Correspondence and requests for materials should be addressed to S.C.


domain: sdv phys

text:
V Vijayarangan
email: vinodini.vijayarangan@cnrs-orleans.fr

A Delalande

S Dozias

J M Pouvesle

E Robert

C Pichon

Cell Permeabilization and Molecular Delivery Following Helium Plasma jet Treatments

Efficient molecular uptake was assessed in HeLa and 4T1 cell lines Interesting results in permeabilization kinetics were observed which opens a new way of plasma treatments fficient delivery of an anticancer agent (doxorubicin) in 4T1 cells was assessed xact plasma mode of action, mechanisms involved in the ring shape permeabilization pattern and specific role of plasma electric field still to be investigated

Introduction

Molecular delivery in cells combining low cytotoxicity and high efficiency using physical techniques remains to be optimized. In this work, we report on the use of a cold atmospheric pressure plasma jet device called Plasma Gun as an innovative strategy for cell membrane permeabilization. In our previous study [1], we focused on evaluating key parameters needed to achieve an efficient molecular delivery. We showed that a low number of pulses (between 1,000 and 100,000) and a 30-minute incubation at 37°C of the treated cells were enhancing molecular uptake in a ring shape pattern with no significant toxicity. In this report, we investigated cell permeabilization kinetics and surprisingly, best permeabilization levels were reached when molecular injections in the cell medium and plasma treatments were not simultaneous. Indeed, best efficiency was measured when the injection was performed a few minutes after plasma. This transient permeabilization was also measured for longer delays of molecular injection which confirms the non-toxic nature of our plasma treatment conditions.

Results

Conclusion

Doxorubicin (DxR) : 544 Da

Perspectives for Cosmetic Applications

Evaluating conditions where cell permeabilization is possible in skin cells (keratinocytes, melanocytes…)

Evaluating skin reaction towards plasma treatments in the stated conditions In Hela cells, permeabilization efficiency increased when PI was added after plasma treatment. It peaked when PI was added 3 minutes after plasma; 39.3% of PI positive cells compared to 18% when PI is added before treatment, and slowly decreased until it reached the control condition (4.25%). Our first hypothesis was that PI might have been degraded by plasma which could explain why molecular uptake was higher when PI was added after plasma treatment. However, we measured the fluorescence of PI solutions treated by plasma and no molecular damage was assessed (data not shown). The decrease in the uptake after 3 minutes illustrates the non-toxicity of the treatment as pores seem to close and restore cell activity as it was before plasma treatments. A continuous increase in molecular uptake would have shown to be a sign of cytotoxicity in cells. Viability measurements in our previous study also confirms these results [1]. These results also shows that when cells were incubated at 4°C, permeabilization efficiency severely decreased (highest value of 7.24% of PI positive cells compared to 33.1% when incubated at 37°C). It is probably correlated with either a decrease in RONS production, a decrease in the speed of the chemical reactions involved in this RONS production and/or the cell mechanisms involved.

Similar experiments with direct plasma treatments were conducted using Doxorubicin as an anticancer drug in 4T1 cells. Results were similar as those with PI as molecular uptake was more efficient when doxorubicin was added after plasma treatment. For the four conditions of treatment with the addition of doxorubicin after plasma, the percentage of PI positive cells were above 25% compared with the addition of the molecule prior treatment (12.95%). Efficient delivery of doxorubicin was achieved in 4T1 cells.

Similar to HeLa[1], a circular impact zone is observed with 4T1 cells in all conditions. Our hypothesis is that plasma electric field might prepare the cells during treatments and that only the cells subjected to a certain amount of plasma electric field are prone to molecular uptake. And that cells are still activated few minutes after plasma treatments. Another hypothesis is that because cells have been subjected to an electric field, when PI is added after treatment, it is not presented to the cells the same way as when PI is present during the electric field sensitization of the cells. Molecular accessibility is then modified and is improved when the molecule is added after treatment.

mm

Application in Drug Delivery

worldscientific.com


domain: sde sdv

text:
G Hemery
email: lhemery@mnhn.fr

Nadia Améziane

Lenaïg G Hemery

Marc Eléaume

V Chavan

Hemery Lg

Barnes Dka

Bohn Jm

Bowden Da

Dahms Hu

Grif- Fiths Hj

Lockhart Sj

Mooi R Rouse

Circumpolar dataset of sequenced specimens of Promachocrinus kerguelensis (Echinodermata, Crinoidea)

Keywords: Antarctica, Crinoidea, Cytochrome Oxydase subunit I, Echinodermata, Phylogeography, Promachocrinus, Southern Ocean, Sub-Antarctic

published or not. The documents may come     Circumpolar dataset of sequenced specimens of Promachocrinus kerguelensis (Echinodermata, Crinoidea)

Project details

Project title: Comprehensive sampling reveals circumpolarity and sympatry in seven mitochondrial lineages of the Southern Ocean crinoid species Promachocrinus kerguelensis (Echinodermata) Personnel: Lenaïg G. Hemery Funding: French ANR ANTFLOCKS (n° 07-BLAN-0213-01); MNHN Paris intern grants (DMPA's BQR, ATMs "Biominéralisation"; "Biodiversité actuelle et fossile; crises, stress, restaurations et panchronisme: le message systématique"; "Taxonomie moléculaire: DNA Barcode et gestion durable des collections").

Study area descriptions/descriptor: The 1307 specimens in this dataset were collected from the Southern Ocean, south of the Sub-Antarctic Front (SAF): Kerguelen Plateau (Kerguelen and Heard islands), Davis Sea, Dumont d'Urville Sea, Ross Sea, Amundsen Sea, West Antarctic Peninsula, East Weddell Sea and Scotia Arc (from the tip of the Antarctic Peninsula and the Bransfield Strait to the South Georgia island). The bathymetric range extended from 65 to 1162 meters deep.

Design description: This dataset was gathered to conduct a circumpolar phylogeographic study of the crinoid species Promachocrinus kerguelensis (Hemery et al. 2012) and designed to spatially improve the sampling of [START_REF] Wilson | Multiple lineages and absence of panmixia in the "circumpolar" crinoid Promachocrinus kerguelensis from the Atlantic sector of Antarctica[END_REF], which was limited to the Atlantic sector of the Southern Ocean. The aim of Hemery et al. (2012) was to test the circumpolarity of the genetic lineages of [START_REF] Wilson | Multiple lineages and absence of panmixia in the "circumpolar" crinoid Promachocrinus kerguelensis from the Atlantic sector of Antarctica[END_REF], and to test whether these lineages represented an under-sampling artifact of a large and genetically diverse metapopulation or whether they were truly representative of the Southern Ocean. The authors used a sampling strategy designed to cover the broadest possible genetic variation and to explore the evolutionary relationships among the seven lineages, in order to be able to conduct population analyses [START_REF] Meyer | DNA barcoding: error rates based on comprehensive sampling[END_REF]. They also wanted to understand the distributional limits of each phylogroup in Promachocrinus kerguelensis to assess the connectivity displayed throughout their range, and to test the "multiple refugia" theory by studying the demographic history of each phylogroup. For this purpose, more than two thousand specimens, sampled during the most recent Antarctic cruises focused on benthic biodiversity and fixed and preserved in a way allowing for DNA extraction and amplification (fixed in ethanol or frozen), were provided by several taxonomists and benthologists from different institutions. Specimen identifications during the sampling cruises were conducted to a higher level allowed by the taxonomic skills of the collectors then checked principally at the Muséum national d'Histoire naturelle, Paris by taxonomists trained to deal with Ant-arctic crinoids. The Cytochrome c Oxydase subunit I (COI) was successfully sequenced for 1307 of these specimens. Both collection data and produced sequences were digitized in appropriate databases, used or ready to be used for publishing purpose (Figure 1).

Data published through GBIF: http://ipt.biodiversity.aq/resource.do?r=proke as an Excel spreadsheet of the dataset, available through the Darwin Core Archive format at http://ipt.biodiversity.aq/archive.do?r=proke.

taxonomic coverage

General taxonomic coverage description: This dataset focuses on the Antarctic comatulid species Promachocrinus kerguelensis [START_REF] Carpenter | Report on the Crinoidea collected during the voyage of H.M.S. Challenger, during the years 1873-76, Part II -The Comatulae[END_REF], the most abundant and morphologically variable comatulid species in the Southern Ocean [START_REF] Speel | Comatulid crinoids from the R/V Eltanin cruises in the Southern Ocean[END_REF]. It corresponds to the 1307 specimens sequenced in Hemery et al. (2012).

taxonomic ranks

Phylum: Echinodermata Class: Crinoidea Order: Comatulida Family: Antedonidae Subfamily: Heliometrinae Genus: Promachocrinus Species: kerguelensis Common names: echinoderm, crinoid, comatulid, feather star

Spatial coverage

General spatial coverage

The specimens of Promachocrinus kerguelensis gathered in this dataset were collected from most of the strategic regions in the Southern Ocean (triangles in Figure 2): the Antarctic continental shelf (East Weddell Sea, Davis Sea, Dumont d'Urville Sea, Ross Sea, Amundsen Sea, West Antarctic Peninsula), the Scotia Arc islands (South Shetland, South Orkney and South Sandwich) and the Sub-Antarctic islands (South Georgia, Kerguelen and Heard). Specimens were sampled at depths ranging from 65 m to 1162 m. This covers most of the known distribution area of this species (black circles in Figure 2), but only a portion of the bathymetric range for this species, which extends from 10 m to 2100 m (Speel and Deardorn 1983).

Coordinates 76°49'58.8"S and 47°12'14.4"S Latitude; 107°24'28.8"W and 170°23'6"E Longitude.

General temporal coverage

The specimens were collected during one to four different cruises per sampling region for a total of 17 cruises from 1996 to 2010 (Figure 3). However, the number of specimens was too variable among cruises to be statistically compared (see details of numbers in the Methods part). Sampling description: The specimens were sampled using several sampling gears, depending on the cruise: agassiz trawls, beam trawls, bottom trawls, box corers, epibenthic sledges (Arntz and Brey 2001, 2003, 2005;Arntz and Gutt 1997;Beaman and O'Brien 2009;Duhamel et al. 2011;Fahrbach 2006;Fütterer et al. 2003;Lockhart et al. 2009). During each cruise, specimens were sorted onboard and then fixed and preserved in 70-95% ethanol or first frozen and subsequently preserved in ethanol. The specimens were curated by each institution once back from the field and digitized in their own databases before the specimens were gathered by the authors in the purpose of the molecular study. Metadata associated with each specimen were extracted from the cruise reports. The molecular data (barcoding) were generated following the protocols described in [START_REF] Ivanova | An inexpensive, automation-friendly protocol for recovering high-quality DNA[END_REF], [START_REF] Eléaume | A large new species of the genus Ptilocrinus (Echinodermata, Crinoidea, Hyocrinidae) from Antarctic seamounts[END_REF] and Hemery et al. (2012).

Quality control description: The initial geo-referencing was done by means of the vessel onboard GPS systems. Samples identification was supervised and checked by Marc Eléaume, crinoid taxonomist at the Muséum national d'Histoire naturelle, Paris, following [START_REF] Clark | A monograph of the existing crinoids. Volume 1 -The comatulids. Part 5 -Suborders Oligophreata (concluded) and Macrophreata[END_REF] taxonomic description of the species, and matched to the World Register of Marine Species (WoRMS). The barcoding was done by Lenaïg G. Hemery at the Muséum national d'Histoire naturelle, Paris, and by the Canadian Center for DNA Barcoding, Toronto, and the Scripps Institution of Oceanography, San Diego, and matched to sequences already available on the Barcode of Life Data System (BOLD: http://www.boldsystems.org/index.php/IDS_OpenIdEngine). All sequences, specimen occurrences and identifications are linked together through unique numbers in BOLD under the public project name PROKE.

Datasets

Dataset description: This dataset has been generated for a molecular study of the Antarctic comatulid species Promachocrinus kerguelensis, improving the geographic coverage of the previous study by [START_REF] Wilson | Multiple lineages and absence of panmixia in the "circumpolar" crinoid Promachocrinus kerguelensis from the Atlantic sector of Antarctica[END_REF]. All the specimens are identified by several types of numbers that are linked together: Sample ID (characteristic of each individual), BOLD ID, GenBank ID and SeqID (all three characteristic of each sequence in different databases), Field Number (when available) and Museum ID. In some cases, the two last identifiers are shared by several individuals identifiable from each other by their own Sample ID. The dataset also includes the name of the institution storing the specimens, the complete taxonomy, names of identifiers and collectors, and information on the sampling itself: cruise names, vessel names, sampling gears, dates, regions, sectors, exact sites (when available), station numbers, latitudes and longitudes in decimal degrees, and depths in meters. This dataset is suitable to be used in studies dealing with, for example, Antarctic and/or crinoid diversity (species richness, distribution patterns), biogeography or habitat / ecological niche modeling.

Figure 1 .

 1 Figure 1. Synoptic of the procedure used to generate the dataset. Yellow exclamatory marks show where the data quality has been checked.

Figure 2 .

 2 Figure 2. Promachocrinus kerguelensis sampling stations in the Southern Ocean. Triangles represent the sampled stations, circles represent the bibliographic data, numbers are sequenced specimens per region (modified from Hemery et al. 2012).

Figure 3 . 1 .

 31 Figure 3. Proportion of specimens per phylogroup per year and sampling region. Acronyms of regions are given in Figure 2, A -F are the names of the 7 COI haplogroups found in Hemery et al. 2012.

  Object name: Darwin Core Archive Circumpolar dataset of sequenced specimens of Promachocrinus kerguelensis (Echinodermata, Crinoidea) Character encoding: UTF-8 Format name: Darwin Core Archive format Format version: 1.0 Distribution: http://ipt.biodiversity.aq/archive.do?r=proke Publication date of data: 2012-03-01 Language: English Metadata language: English Date of metadata creation: 2012-04-25 Hierarchy level: Dataset

Acknowledgements

The authors thank Sarah Henkel and the two anonymous reviewers who helped to improve this manuscript, and all the contributors who furnished the samples: Anderson O, Barnes DKA, Bohn JM, Bowden DA, Brey T, Constable A, Dahms HU, Duhamel G, Griffiths HJ, Hautecoeur M, Hibberd T, Linse K, Lockhart SJ, Lodde E, Mills S, Mooi R, Rouse GW, Sands CJ, Schiaparelli S, Schnabel K, Wilson NG.

Appendix

Sampling data associated to the 1307 specimens of Promachocrinus kerguelensis sequenced in Hemery et al. (2012). (doi: 10.3897/zookeys.315.5673.app) File format: ScanVec CASmate Sign File (scv).

Explanation note: Each sample is associated to three unique sequence IDs (BOLD ID, GenBank ID and SeqID); Haplotype and Clade refer back to the genetic data from Hemery et al. (2012); Latitude and Longitude are given in decimal degrees; Depth is given in meters.

Copyright notice: This dataset is made available under the Open Database License (http://opendatacommons.org/licenses/odbl/1.0/). The Open Database License (ODbL) is a license agreement intended to allow users to freely share, modify, and use this Dataset while maintaining this same freedom for others, provided that the original source and author(s) are credited.

Citation: Hemery LG, Améziane N, Eléaume M (2013) Circumpolar dataset of sequenced specimens of Promachocrinus kerguelensis (Echinodermata, Crinoidea). ZooKeys 315: 55-64. doi: 10.3897/zookeys.315.5673 Sampling data associated to the 1307 specimens of Promachocrinus kerguelensis sequenced in Hemery et al. (2012). doi: 10.3897/ zookeys.315.5673.app