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Michio Kondo - One of the best experts on this subject based on the ideXlab platform.

  • Microcrystalline Silicon solar cells with 10 5 efficiency realized by improved photon absorption via periodic textures and highly transparent conductive oxide
    Applied Physics Express, 2013
    Co-Authors: Hitoshi Sai, Takuya Matsui, Kimihiko Saito, Takashi Koida, Isao Yoshida, Michio Kondo
    Abstract:

    We developed advanced light management techniques and applied them to single-junction Microcrystalline Silicon solar cells to improve their current density and conversion efficiency. A high short-circuit current density of 30.8 mA/cm2 is attained in a 3-µm-thick cell aided by the superior light-trapping effect of periodically textured back reflectors, and by the reduced absorption loss from the high-mobility transparent conductive oxide films. In addition, an unprecedented efficiency of 10.5% is independently confirmed in a 1.8-µm-thick cell with the same structure. These results indicate the importance of light management for further efficiency improvements in thin-film Silicon solar cells.

  • relationship between the cell thickness and the optimum period of textured back reflectors in thin film Microcrystalline Silicon solar cells
    Applied Physics Letters, 2013
    Co-Authors: Kimihiko Saito, Nana Hozuki, Michio Kondo
    Abstract:

    Periodically textured back reflectors with hexagonal dimple arrays are applied to thin-film Microcrystalline Silicon (μc-Si:H) solar cells. When the textures have a moderate aspect ratio, the optimum period for obtaining a high short circuit current density (JSC ) is found to be equal to or slightly larger than the cell thickness. If the cell thickness exceeds the texture period, the cell surface tends to be flattened and texture-induced defects are generated, which constrain the improvement in JSC . Based on these findings, we have fabricated optimized μc-Si:H cells achieving a high efficiency exceeding 10% and a JSC of 30 mA/cm2.

  • enhanced photocurrent and conversion efficiency in thin film Microcrystalline Silicon solar cells using periodically textured back reflectors with hexagonal dimple arrays
    Applied Physics Letters, 2012
    Co-Authors: Kimihiko Saito, Michio Kondo
    Abstract:

    Periodically textured back reflectors with hexagonal dimple arrays are applied to thin-film Microcrystalline Silicon (μc-Si:H) solar cells for enhancing their photon absorption and photovoltaic performance. In a systematic survey of 1 -μm-thick μc-Si:H cells, the best performance is obtained with a period of 1.5 μm and an aspect ratio of 0.20–0.25 with a high current density exceeding 26 mA/cm2 and a marked efficiency of 10.1%. These results demonstrate the high potential of periodic textures or surfacegratings for improving the conversion efficiency of thin-film Silicon solar cells.

  • investigation of crystalline orientation factor in Microcrystalline Silicon thin film deposition
    Physica Status Solidi (a), 2010
    Co-Authors: Michio Kondo, Kimihiko Saito
    Abstract:

    Crystalline orientation factors in Microcrystalline Silicon (μc-Si) deposition are investigated by the triode-plasma enhanced chemical vapor deposition (PECVD) method and conventional diode-PECVD with optical emission spectroscopy (OES). The existence of more important factors for the orientation than the ion and the [H]/[SiH x ] ratio on the growing surface is suggested from the SiH 4 flow rate and the mesh-electrode gap dependence of the orientation and the crystallinity in triode-PECVD. Improvement of the crystallinity and the independent orientation of the following film on the seed-layer offer the deposition radicals to act a key role for the crystalline growth direction. The oligomerized-silane radical (probably dimeric radical) is proposed as an orientation factor by the relation of SiH* emission intensity on the deposition rate and the orientation.

  • high rate deposition of Microcrystalline Silicon p i n solar cells in the high pressure depletion regime
    Journal of Applied Physics, 2008
    Co-Authors: Ahm Arno Smets, T Matsui, Michio Kondo
    Abstract:

    Hydrogenated Microcrystalline Silicon films (μc-Si:H) deposited at high deposition rates (∼2 nm/s) by means of the very-high-frequency (VHF) deposition technique in the high pressure depletion regime have been integrated into single junction p-i-n solar cells. It is demonstrated that μc-Si:H solar cells can be optimized using a twofold approach. First the bulk properties, deposited under steady-state plasma conditions, are optimized by monitoring the presence of crystalline grain boundaries in μc-Si:H. These hydrogenated crystalline grain boundaries can easily be detected via the crystalline surface hydrides contribution to the narrow high stretching modes by infrared transmission spectroscopy. The crystalline grain boundaries suffer from postdeposition oxidation which results in a reduced red response of the solar cell. The absence of these crystalline surfaces in an as-deposited μc-Si:H matrix reflects the device grade Microcrystalline bulk material. Second, the prevention of silane backdiffusion from t...

Reinhard Carius - One of the best experts on this subject based on the ideXlab platform.

  • performance of p and n side illuminated Microcrystalline Silicon solar cells following 2 mev electron bombardment
    Applied Physics Letters, 2012
    Co-Authors: V Smirnov, Reinhard Carius, Oleksandr Astakhov, Bart E Pieters, Yu Petrusenko, V Borysenko, F Finger
    Abstract:

    The impact of defects on the performance of p- and n-side illuminated Microcrystalline Silicon solar cells is investigated. The absorber layer spin density NS is controlled over some two orders of magnitude by electron bombardment and subsequent annealing steps. At increased NS (between 3 × 1016 and 1018 cm−3), performance of n-side illuminated cells is much more strongly reduced relative to p-side illuminated cells, particularly with regard to short circuit current density. Quantum efficiency measurements indicate a corresponding strong asymmetry in wavelength-dependence, which has been successfully reproduced by numerical device simulations.

  • variation in absorber layer defect density in amorphous and Microcrystalline Silicon thin film solar cells with 2 mev electron bombardment
    Japanese Journal of Applied Physics, 2012
    Co-Authors: V Smirnov, Reinhard Carius, Oleksandr Astakhov, Yu Petrusenko, V Borysenko, F Finger
    Abstract:

    The effect of the defect density in hydrogenated amorphous and Microcrystalline Silicon (a-Si:H and µc-Si:H) absorber layers on the performance of thin film solar cells was investigated. The defect density was varied reproducibly over more than two orders of magnitude by 2 MeV electron bombardment and subsequent thermal annealing. Considerable quantitative and qualitative differences were observed for the dependences of the cells parameters on the defect densities of a-Si:H and µc-Si:H. The experimental data suggest further possible improvement of µc-Si:H based solar cells with further reduced defect densities, while for a-Si:H based solar cells, a saturation of performance is observed below a defect density of about 1016 cm-3. Moreover, the experimental data provide an excellent database for numerical simulation over a range unavailable so far particularly in µc-Si:H based solar cells.

  • plasmonic reflection grating back contacts for Microcrystalline Silicon solar cells
    Applied Physics Letters, 2011
    Co-Authors: Ulrich W Paetzold, Etienne Moulin, Dirk Michaelis, W Bottler, C Wachter, V Hagemann, M Meier, Reinhard Carius
    Abstract:

    We report on the fabrication and optical simulation of a plasmonic light-trapping concept for Microcrystalline Silicon solar cells, consisting of silver nanostructures arranged in square lattice at the ZnO:Al/Ag back contact of the solar cell. Those solar cells deposited on this plasmonic reflection grating back contact showed an enhanced spectral response in the wavelengths range from 500 nm to 1000 nm, when comparing to flat solar cells. For a particular period, even an enhancement of the short circuit current density in comparison to the conventional random texture light-trapping concept is obtained. Full three-dimensional electromagnetic simulations are used to explain the working principle of the plasmonic light-trapping concept.

  • relationship between defect density and charge carrier transport in amorphous and Microcrystalline Silicon
    Physical Review B, 2009
    Co-Authors: Oleksandr Astakhov, F Finger, Reinhard Carius, Yu Petrusenko, V Borysenko, D Barankov
    Abstract:

    The influence of dangling-bond defects and the position of the Fermi level on the charge carrier transport properties in undoped and phosphorous doped thin-film Silicon with structure compositions all the way from highly crystalline to amorphous is investigated. The dangling-bond density is varied reproducibly over several orders of magnitude by electron bombardment and subsequent annealing. The defects are investigated by electron-spin-resonance and photoconductivity spectroscopies. Comparing intrinsic amorphous and Microcrystalline Silicon, it is found that the relationship between defect density and photoconductivity is different in both undoped materials, while a similar strong influence of the position of the Fermi level on photoconductivity via the charge carrier lifetime is found in the doped materials. The latter allows a quantitative determination of the value of the transport gap energy in Microcrystalline Silicon. The photoconductivity in intrinsic Microcrystalline Silicon is, on one hand, considerably less affected by the bombardment but, on the other hand, does not generally recover with annealing of the defects and is independent from the spin density which itself can be annealed back to the as-deposited level. For amorphous Silicon and material prepared close to the crystalline growth regime, the results for nonequilibrium transport fit perfectly to a recombination model basedmore » on direct capture into neutral dangling bonds over a wide range of defect densities. For the heterogeneous Microcrystalline Silicon, this model fails completely. The application of photoconductivity spectroscopy in the constant photocurrent mode (CPM) is explored for the entire structure composition range over a wide variation in defect densities. For amorphous Silicon previously reported linear correlation between the spin density and the subgap absorption is confirmed for defect densities below 10{sup 18} cm{sup -3}. Beyond this defect level, a sublinear relation is found i.e., not all spin-detected defects are also visible in the CPM spectra. Finally, the evaluation of CPM spectra in defect-rich Microcrystalline Silicon shows complete absence of any correlation between spin-detected defects and subband gap absorption determined from CPM: a result which casts considerable doubt on the usefulness of this technique for the determination of defect densities in Microcrystalline Silicon. The result can be related to the inhomogeneous structure of Microcrystalline Silicon with its consequences on transport and recombination processes.« less

  • highly transparent Microcrystalline Silicon carbide grown with hot wire chemical vapor deposition as window layers in n i p Microcrystalline Silicon solar cells
    Applied Physics Letters, 2007
    Co-Authors: Y Huang, F Finger, A Gordijn, Arup Dasgupta, Reinhard Carius
    Abstract:

    Microcrystalline Silicon carbide (μc-SiC) films were prepared using hot wire chemical vapor deposition at low substrate temperature. The μc-SiC films were employed as window layers in Microcrystalline Silicon (μc-Si:H) n-i-p solar cells. Quantum efficiency (QE) and short circuit current density (JSC) in these n-side illuminated n-i-p cells were significantly higher than in standard p-i-n cells. A high QE current density of 26.7mA∕cm2 was achieved in an absorber layer thickness of 2μm. The enhanced JSC was attributed to the wide band gap of the μc-SiC layer and a sufficiently high hole drift mobility in μc-Si:H absorber layer.

F Finger - One of the best experts on this subject based on the ideXlab platform.

  • Microcrystalline Silicon oxygen alloys for application in Silicon solar cells and modules
    Solar Energy Materials and Solar Cells, 2013
    Co-Authors: Andreas Lambertz, R E I Schropp, Vladimir Smirnov, T Merdzhanova, Kang K Ding, Stefan Haas, G Jost, F Finger
    Abstract:

    Abstract Microcrystalline Silicon oxide (µc-SiO x :H) alloys prepared by plasma enhanced chemical vapor deposition (PECVD) represent a versatile material class for opto-electronic applications especially for thin-film and wafer based Silicon solar cells. The material is a phase mixture of Microcrystalline Silicon (µc-Si:H) and amorphous Silicon oxide (a-SiO x :H). The possibility to enhance the optical band gap energy and to adjust the refractive index over a considerable range, together with the possibility to dope the material p-type as well as n-type, makes μc-SiO x :H an ideal material for the application as window layer, as intermediate reflector (IR), and as back reflector in thin-film Silicon solar cells. Analogously, μc-SiO x :H is a suitable material for p- and n-type contact layers in Silicon hetero junction (SHJ) solar cells. The present paper gives an overview on the range of physical parameters (refractive index, optical band gap, conductivity) which can be covered by this material by variation of the deposition conditions. The paper focuses on the interdependence between these material properties and optical improvements for amorphous Silicon/Microcrystalline Silicon (a-Si:H/µc-Si:H) tandem solar cells prepared on different substrates, such as Asahi (VU) and sputtered ZnO:Al. It gives a guideline on possible optical gains when using doped µc-SiO x :H in Silicon based solar cells. As intermediate reflector in a-Si:H/µc-Si:H tandem cells µc-SiO x :H leads to an effective transfer of short circuit current generation from the bottom cell to the top cell resulting in a possible thickness reduction of the top cell by 40%. Within another series of solar cells shown in this paper a short circuit current density of 14.1 mA/cm² for an a-Si:H/µc-Si:H tandem solar cell with a µc-SiO x :H intermediate reflector is demonstrated. A SHJ solar cell on a flat (non-textured) wafer using p- and n-type doped µc-SiO x :H contact layers with an effective area efficiency of 19.0% is also presented.

  • performance of p and n side illuminated Microcrystalline Silicon solar cells following 2 mev electron bombardment
    Applied Physics Letters, 2012
    Co-Authors: V Smirnov, Reinhard Carius, Oleksandr Astakhov, Bart E Pieters, Yu Petrusenko, V Borysenko, F Finger
    Abstract:

    The impact of defects on the performance of p- and n-side illuminated Microcrystalline Silicon solar cells is investigated. The absorber layer spin density NS is controlled over some two orders of magnitude by electron bombardment and subsequent annealing steps. At increased NS (between 3 × 1016 and 1018 cm−3), performance of n-side illuminated cells is much more strongly reduced relative to p-side illuminated cells, particularly with regard to short circuit current density. Quantum efficiency measurements indicate a corresponding strong asymmetry in wavelength-dependence, which has been successfully reproduced by numerical device simulations.

  • variation in absorber layer defect density in amorphous and Microcrystalline Silicon thin film solar cells with 2 mev electron bombardment
    Japanese Journal of Applied Physics, 2012
    Co-Authors: V Smirnov, Reinhard Carius, Oleksandr Astakhov, Yu Petrusenko, V Borysenko, F Finger
    Abstract:

    The effect of the defect density in hydrogenated amorphous and Microcrystalline Silicon (a-Si:H and µc-Si:H) absorber layers on the performance of thin film solar cells was investigated. The defect density was varied reproducibly over more than two orders of magnitude by 2 MeV electron bombardment and subsequent thermal annealing. Considerable quantitative and qualitative differences were observed for the dependences of the cells parameters on the defect densities of a-Si:H and µc-Si:H. The experimental data suggest further possible improvement of µc-Si:H based solar cells with further reduced defect densities, while for a-Si:H based solar cells, a saturation of performance is observed below a defect density of about 1016 cm-3. Moreover, the experimental data provide an excellent database for numerical simulation over a range unavailable so far particularly in µc-Si:H based solar cells.

  • hydrogenated amorphous Silicon oxide containing a Microcrystalline Silicon phase and usage as an intermediate reflector in thin film Silicon solar cells
    Journal of Applied Physics, 2011
    Co-Authors: Andreas Lambertz, Thomas Grundler, F Finger
    Abstract:

    To further improve the stability of amorphous/Microcrystalline Silicon (a-Si:H/μc-Si:H) tandem solar cells, it is important to reduce the thickness of the a-Si:H top cell. This can be achieved by introduction of an intermediate reflector between the a-Si:H top and the μc-Si:H bottom cell which reflects light back into the a-Si:H cell and thus, increases its photocurrent at possibly reduced thickness. Microcrystalline Silicon oxide (μc-SiOx:H) is used for this purpose and the trade-off between the material’s optical, electrical and structural properties is studied in detail. The material is prepared with plasma enhanced chemical vapor deposition from gas mixtures of silane, carbon dioxide and hydrogen. Phosphorus doping is used to make the material highly conductive n-type. Intermediate reflectors with different optical and electrical properties are then built into tandem solar cells as part of the inner n/p-recombination junction. The quantum efficiency and the reflectance of these solar cells are evaluat...

  • hydrogenated amorphous Silicon oxide containing a Microcrystalline Silicon phase and usage as an intermediate reflector in thin film Silicon solar cells
    Journal of Applied Physics, 2011
    Co-Authors: Andreas Lambertz, Thomas Grundler, F Finger
    Abstract:

    To further improve the stability of amorphous/Microcrystalline Silicon (a-Si:H/μc-Si:H) tandem solar cells, it is important to reduce the thickness of the a-Si:H top cell. This can be achieved by introduction of an intermediate reflector between the a-Si:H top and the μc-Si:H bottom cell which reflects light back into the a-Si:H cell and thus, increases its photocurrent at possibly reduced thickness. Microcrystalline Silicon oxide (μc-SiOx:H) is used for this purpose and the trade-off between the material’s optical, electrical and structural properties is studied in detail. The material is prepared with plasma enhanced chemical vapor deposition from gas mixtures of silane, carbon dioxide and hydrogen. Phosphorus doping is used to make the material highly conductive n-type. Intermediate reflectors with different optical and electrical properties are then built into tandem solar cells as part of the inner n/p-recombination junction. The quantum efficiency and the reflectance of these solar cells are evaluated to find optical gains and losses due to the intermediate reflector. Suitable intermediate reflectors result in a considerable increase in the top cell current density which allows a reduction of the a-Si:H top cell thickness of about 40% for a tandem cell while keeping the current density of the device constant.

Friedhelm Finger - One of the best experts on this subject based on the ideXlab platform.

  • Silicon heterojunction solar cell with amorphous Silicon oxide buffer and Microcrystalline Silicon oxide contact layers
    Physica Status Solidi-rapid Research Letters, 2012
    Co-Authors: Kaining Ding, Urs Aeberhard, Friedhelm Finger
    Abstract:

    This Letter reports on the fabrication and characterization of Silicon heterojunction solar cells with Silicon oxide based buffer (intrinsic amorphous Silicon oxide) and contact layers (doped Microcrystalline Silicon oxide) on flat p-type wafers. The critical dependency of the cell performance on the front and rear buffer layer thickness reveals a trade-off between the open circuit voltage Voc and the fill factor FF. At the optimum, the highest efficiency of 18.5% (active area = 0.67 cm2) was achieved with Voc = 664 mV, short circuit current Jsc = 35.7 mA/cm2 and FF = 78.0%. (© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

  • Open circuit voltage improvement of high-deposition-rate Microcrystalline Silicon solar cells by hot wire interface layers
    Applied Physics Letters, 2005
    Co-Authors: Y. Mai, Helmut Stiebig, Reinhard Carius, Stefan Klein, Xinhua Geng, Friedhelm Finger
    Abstract:

    Significant improvement in open circuit voltage and fill factor was achieved for Microcrystalline Silicon (μc‐Si:H) solar cells deposited by plasma-enhanced chemical vapor deposition (PECVD) by the incorporation of an intrinsic μc‐Si:Hp∕i buffer layer fabricated by hot-wire (HW) CVD. The improved p∕i interface quality, likely due to the ion-free deposition on the p layers in the HWCVD process, was concluded from a considerably enhanced blue light response in such solar cells. Using this buffer layer concept allows the authors to apply high deposition rate PECVD processes for the μc‐Si:Hi layer material, yielding a high efficiency of 10.3% for a single junction μc‐Si:H solar cell.

  • structure adjustment during high deposition rate growth of Microcrystalline Silicon solar cells
    Applied Physics Letters, 2004
    Co-Authors: Y. Mai, Stefan Klein, Xinhua Geng, Friedhelm Finger
    Abstract:

    Preparation of Microcrystalline Silicon for solar cell applications is investigated under high-pressure, high-power conditions with plasma-enhanced chemical vapor deposition at 95MHz. It is found that the deposition rate depends mainly on the amount of silane in the reaction zone. Changes in the discharge power affect the deposition rate very little. This points to silane depletion under these process conditions. The amount of H radicals, on the other hand, increases with increasing discharge power and leads to structure changes of the material. Making use of this effect, optimum phase mixture material at the transition from highly crystalline to amorphous growth can be deposited at considerably higher deposition rates without loss in solar cell performance.

  • improvement of grain size and deposition rate of Microcrystalline Silicon by use of very high frequency glow discharge
    Applied Physics Letters, 1994
    Co-Authors: Friedhelm Finger, M Luysberg, P Hapke, H Wagner, Reinhard Carius, M Scheib
    Abstract:

    The influence of the plasma excitation frequency on the growth conditions and the material properties of Microcrystalline Silicon prepared by plasma enhanced chemical vapor deposition at low deposition temperature is investigated. It is found that an increase of the plasma excitation frequency leads to a simultaneous increase of the growth rate, the grain size, and the Hall mobility of Microcrystalline Silicon. This is attributed to an effective selective etching of disordered material creating more space to develop crystalline grains, while also more species for faster growth of the crystallites are available.

J Meier - One of the best experts on this subject based on the ideXlab platform.

  • LIGHT SCATTERING IN Microcrystalline Silicon THIN FILM CELLS
    2015
    Co-Authors: Ales Poruba, J Meier, P Torres, J. Springer, Z. Remeš, M. Van Ek, A. Fejfar, A. Shah
    Abstract:

    ABSTRACT: Different optical characterization methods were applied to a series of Microcrystalline Silicon thin films, either as grown, textured, or subsequently polished, mirror-like. They reveal contributions of bulk and surface light scattering effects to the phenomenon of optical absorption enhancement. The enhanced light absorption in textured layers is mainly due to a longer optical path as a result of an efficient diffuse light scattering at the textured film surface. Root mean square surface roughness of about 40nm is sufficient for completely diffusive scattering of Silicon/metal back reflector. Keywords

  • influence of the substrate s surface morphology and chemical nature on the nucleation and growth of Microcrystalline Silicon
    Thin Solid Films, 2005
    Co-Authors: Evelyne Vallatsauvain, Julien Bailat, J Meier, X Niquille, U Kroll, A. Shah
    Abstract:

    Hydrogenated Microcrystalline Silicon (μc-Si:H) layers about 500 nm thick were deposited in the same run on flat and rough substrates (rms = 60 nm) of various chemical nature. This study reveals that the spatial distribution of the Microcrystalline/amorphous phases within the layer depends on the substrate's topography. The influence of the chemical nature of the substrate is shown to be preponderant on the layers nucleation. In particular, this study shows that nucleation density is the highest on plasma enhanced chemical vapor deposited Silicon dioxide, whereas it is independent of the substrate's surface topography. Finally, the interpretation of Micro-Raman experiments for the evaluation of the respective volume fractions of amorphous/Microcrystalline phases in the layers is discussed in relation with their spatial distribution. © 2005 Elsevier B.V. All rights reserved.

  • potential of amorphous and Microcrystalline Silicon solar cells
    Thin Solid Films, 2004
    Co-Authors: J Meier, U Kroll, J Spitznagel, C Bucher, T Moriarty, Arvind Shah
    Abstract:

    Low pressure chemical vapour deposition (LP-CVD) ZnO as front transparent conductive oxide (TCO), developed at IMT, has excellent light-trapping properties for a-Si:H p-i-n single-junction and 'micromorph' (amorphous/Microcrystalline Silicon) tandem solar cells. A stabilized record efficiency of 9.47% has independently been confirmed by NREL for an amorphous Silicon single-junction p-i-n cell (∼1 cm2) deposited on LP-CVD ZnO coated glass. Micromorph tandem cells with an initial efficiency of 12.3% show after light-soaking a stable performance of 10.8%. The monolithic series connection by laser-scribing for module fabrication has been developed at IMT as well, for both amorphous single-junction and micromorph tandem cells in combination with the LP-CVD ZnO technique. Mini-modules (areas between 22 and 24 cm2) with an aperture efficiency of 8.7% in the case of amorphous single-junction p-i-n cells (independently confirmed by NREL), and of 9.8% in the case of micromorph tandem cells, have been obtained. Micromorph tandem cells with an intermediate TCO reflector between the amorphous top and the Microcrystalline bottom cell show an almost stable performance (η=10.7%) with respect to light-soaking. © 2003 Elsevier B.V. All rights reserved.

  • relationship between raman crystallinity and open circuit voltage in Microcrystalline Silicon solar cells
    Solar Energy Materials and Solar Cells, 2004
    Co-Authors: C. Droz, L. Feitknecht, Evelyne Vallatsauvain, Julien Bailat, J Meier, Arvind Shah
    Abstract:

    A series of nip-type Microcrystalline Silicon (mc-Si:H) single-junction solar cells has been studied by electrical characterisation, by transmission electron microscopy (TEM) and by Raman spectroscopy using 514 and 633 nm excitation light and both top- and bottomillumination. Thereby, a Raman crystallinity factor indicative of crystalline volume fraction is introduced and applied to the interface regions, i.e. to the mixed amorphous-Microcrystalline layers at the top and at the bottomof entire cells. Results are compared with TEM observations for one of the solar cells. Similar Raman and electrical investigations have been conducted also on pin-type mc-Si:H single-junction solar cells. Experimental data show that for all nip and pin mc-Si:H solar cells, the open-circuit voltage linearly decreases as the average of the Raman crystallinity factors for top and bottom interface regions increases.

  • high rate growth of Microcrystalline Silicon by vhf gd at high pressure
    Thin Solid Films, 2003
    Co-Authors: U. Graf, C. Droz, Evelyne Vallatsauvain, Julien Bailat, J Meier, U Kroll, A. Shah
    Abstract:

    Microcrystalline Silicon growth using very high frequency-glow discharge PECVD has been studied under conditions of high pressure and high VHF-power conditions. Hereby, the influence of the total gas flow and the silane concentration on the deposition rate has been investigated. Deposition rates of over 25 A/s have been achieved at relatively low total gas flows of 100 sccm. These high-rate films show device-grade quality with respect to subband gap absorption and Microcrystalline structure. Dark conductivity measurements reveal midgap character and transmission electron microscopy investigations confirm a highly crystalline microstructure from the bottom to the top of the μc-Si:H films. These high-rate μc-Si:H layers are very interesting candidates for solar cell and other devices.