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Université de Neuchâtel

Scope of VHF plasma deposition for thin-film silicon solar cells

Keppner, Herbert ; Kroll, U. ; Torres, Pedro ; Meier, Johannes ; Fischer, Diego ; Goetz, M. ; Tscharner, R. ; Shah, Arvind

In: Conference Record of the 25th IEEE Photovoltaic Specialists Conference, 1996, p. 669-672

The world-wide attempts in obtaining thin-film crystalline silicon are reviewed. Based on literature published so far, it appears that high-temperature manufacturing steps seem to be unavoidable for obtaining high conversion efficiencies of crystalline silicon based solar cells. High process temperatures are in contradiction for the use of low-cost substrates like e.g. glass or aluminium. Such...

Université de Neuchâtel

Preparation of undoped and doped microcrystalline silicon(μc-Si:H) by VHF-GD for p-i-n solar cells

Flückiger, R. ; Meier, Johannes ; Keppner, Herbert ; Goetz, M. ; Shah, Arvind

In: Conference Record of the 23th IEEE Photovoltaic Specialists Conference, 1993, p. 839-844

The electronic transport properties of μc-Si:H materials were investigated. The μc-Si:H was deposited by the very high frequency-glow discharge (VHF-GD) technique at an RF-excitation of 70 MHz. Very thin

doped layers (100-400 Å) were studied. Conductivities higher than 10-3 (Ω cm)-1 could be achieved for films thicker than 150 Å. The as-deposited μc-Si:H is a slightly...

Université de Neuchâtel

Intrinsic microcrystalline silicon (μc-Si:H)-a promising newthin film solar cell material

Meier, Johannes ; Dubail, S. ; Flückiger, R. ; Fischer, Diego ; Keppner, Herbert ; Shah, Arvind

In: Conference Record of the Twenty Fourth IEEE Photovoltaic Specialists Conference (1994 IEEE First World Conference on Photovoltaic Energy Conversion), 1994, vol. 1, p. 409-412

“Compensated” microcrystalline silicon is obtained by adding 8-20 ppm diborane in the plasma gas phase. p-i-n cells with such i-layers have increased infrared sensitivity when compared to a-Si:H p-i-n cells. The preparation of the world's first “mixed stacked” a-Si:H/μc-Si:H tandem cell with an initial efficiency of 9.1% is reported. The μc-Si:H cells showed no degradation of the cell...

Université de Neuchâtel

High-Ts amorphous top cells for increased top cell currents in micromorph tandem cells

Platz, R. ; Hof, Ch. ; Fischer, Diego ; Meier, Johannes ; Shah, Arvind

In: Solar Energy Materials and Solar Cells, 1998, vol. 53, no. 1-2, p. 1-13

In the present paper, the authors discuss the application of amorphous p–i–n solar cells containing i-layers which are deposited at high substrate temperatures as top cells in amorphous silicon/microcrystalline silicon tandem (“micromorph”) solar cells. Increasing the substrate temperature for the deposition of intrinsic a-Si : H results in a reduced optical gap. The optical absorption is...

Université de Neuchâtel

Enhanced optical absorption in microcrystalline silicon

Beck, N. ; Meier, Johannes ; Fric, J. ; Remeš, Z. ; Poruba, A. ; Flückiger, R. ; Pohl, J. ; Shah, Arvind ; Vaněček, Milan

In: Journal of Non-Crystalline Solids, 1996, vol. 198-200, p. 903-906

An enhanced optical absorption, compared to crystalline silicon, was observed in the above gap region together with very low defect-connected absorption in microcrystalline silicon (μc-Si:H) prepared by very high frequency glow discharge technique at 70 MHz. As the μc-Si:H material has a very low fraction of amorphous phase, a ‘crystalline silicon like’ absorption model is proposed which...

Université de Neuchâtel

On the transport properties of microcrystalline silicon

Fejfar, A. ; Beck, N. ; Stuchlíková, H. ; Wyrsch, Nicolas ; Torres, Pedro ; Meier, Johannes ; Shah, Arvind ; Kočka, J.

In: Journal of Non-Crystalline Solids, 1998, vol. 227-230, p. 1006-1010

To determine the charge collection mechanism in hydrogenated microcrystalline silicon (μc-Si:H) solar cells, we have measured the electronic transport properties of μc-Si:H by time-of-flight and by ac capacitance and conductance on a unique 5.6 μm thick sample. We found the electron drift mobility μD=2.8±0.2 cm2 V−1 s−1, thermally...

Université de Neuchâtel

From amorphous to microcrystalline silicon films prepared by hydrogen dilution using the VHF (70 MHz) GD technique

Kroll, U. ; Meier, Johannes ; Torres, Pedro ; Pohl, J. ; Shah, Arvind

In: Journal of Non-Crystalline Solids, 1998, vol. 227-230, p. 68-72

The amorphous and microcrystalline silicon films have been prepared by hydrogen dilution from pure silane to silane concentrations ≥1.25%. At silane concentrations of less than 10%, a transition from the amorphous phase to the microcrystalline phase can be observed. X-ray diffraction spectroscopy indicates a preferential growth of the crystallites in the [220] direction. Additionally, the...

Université de Neuchâtel

Microcrystalline p–i–n cells: a drift-controlled device?

Wyrsch, Nicolas ; Torres, Pedro ; Meier, Johannes ; Shah, Arvind

In: Journal of Non-Crystalline Solids, 1998, vol. 227-230, p. 1272-1276

The objective of this paper is to get more insight into the physics of microcrystalline silicon based solar cell by studying electric field profiles, spectral responses and current–voltage characteristics. Based on a comparison with a-Si:H p–i–n and c-Si p–n diodes, we concluded that μc-Si:H p–i–n devices are not field-controlled despite the presence of a high electric field...

Université de Neuchâtel

Recent progress in micromorph solar cells

Meier, Johannes ; Dubail, S. ; Cuperus, J. ; Kroll, U. ; Platz, R. ; Torres, Pedro ; Anna Selvan, J. A. ; Pernet, P. ; Beck, N. ; Pellaton Vaucher, N. ; Hof, Ch. ; Fischer, Diego ; Keppner, Herbert ; Shah, Arvind

In: Journal of Non-Crystalline Solids, 1998, vol. 227-230, p. 1250-1256

Recently, we have demonstrated that intrinsic hydrogenated microcrystalline silicon, as deposited by the very high frequency glow-discharge technique, can be used as the active layers of p–i–n solar cells. Our microcrystalline silicon represents a new form of thin film crystalline silicon that can be deposited (in contrast to any other approach found in literature) at substrate temperatures...

Université de Neuchâtel

Electron spin resonance and optical characterization of defects in microcrystalline silicon

Vaněček, Milan ; Poruba, A. ; Remeš, Z. ; Rosa, J. ; Kamba, S. ; Vorlíček, S. ; Meier, Johannes ; Shah, Arvind

In: Journal of Non-Crystalline Solids, 2000, vol. 266-269, p. 519-523

Electron spin resonance (ESR), constant photocurrent method (CPM), photothermal deflection spectroscopy (PDS), Raman and IR spectroscopy have been used to measure microcrystalline silicon films. Besides standard defects with a g-value of 2.0055, new defects with a g-value ~2.0030 have been created during annealing this material. Proportionality between the subgap optical absorption...