Université de Neuchâtel

Determination of the quality of a-Si:H films: “true”transport parameters

Beck, N. ; Shah, Arvind ; Wyrsch, Nicolas

In: Conference Record of the Twenty Fourth IEEE Photovoltaic Specialists Conference (1994 IEEE First World Conference on Photovoltaic Energy Conversion), 1994, vol. 1, p. 476-479

For the characterisation of a-Si:H layers, steady-state photoconductivity (SSPC) and steady-state photocarrier grating (SSPG) are currently used. But the μτ-products deduced from these measurements are a function of the prevailing dangling bond occupation in the film and, thus, are not a measure of material quality. In the present paper the authors introduce the product...

Université de Neuchâtel

Correlation between transport properties of a-Si:H layers and cell performances incorporating these layers

Wyrsch, Nicolas ; Beck, N. ; Hof, Ch. ; Goerlitzer, M. ; Shah, Arvind

In: Journal of Non-Crystalline Solids, 1996, vol. 198-200, p. 238-241

Using the new ‘quality parameter’, μ0τ0, the authors were able to show, for the first time, a clear correlation between transport properties of a series of a-Si:H films (grown at various deposition temperatures) and the efficiency of p-i-n cells incorporating the same material as i-layer. In this paper, additional experimental data are presented sustaining, on one...

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

Optical properties of microcrystalline materials

Vaněček, Milan ; Poruba, A. ; Remeš, Z. ; Beck, N. ; Nesládek, M.

In: Journal of Non-Crystalline Solids, 1998, vol. 227-230, p. 967-972

We use optical, photocurrent and photothermal deflection spectroscopies to study defects in microcrystalline silicon (μc-Si) thin films and diamond layers. Enhanced light absorption in μc-Si films and solar cells is due to several contributions: light scattering, change in the optical transition probability for strained and surface atoms and residual amorphous fraction. Low defect...

Université de Neuchâtel

Structural properties and electronic transport in intrinsic microcrystalline silicon deposited by the VHF-GD technique

Goerlitzer, M. ; Torres, Pedro ; Beck, N. ; Wyrsch, Nicolas ; Keppner, Herbert ; Pohl, J. ; Shah, Arvind

In: Journal of Non-Crystalline Solids, 1998, vol. 227-230, p. 996-1000

A series of microcrystalline samples was deposited by the very high frequency glow discharge (VHF-GD) technique, with various input powers while keeping all the other parameters of deposition constant. The goal was to correlate transport and structural properties and avoid as much as possible the problem of a variation of the Fermi level between the samples. The observed decrease of the...

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

Mobility lifetime product—A tool for correlating a-Si:H film properties and solar cell performances

Beck, N. ; Wyrsch, Nicolas ; Hof, Ch. ; Shah, Arvind

In: Journal of Applied Physics, 1996, vol. 79, no. 12, p. 9361-9368

The missing correlation between film characteristics and α-Si:H-based p-i-n solar cells is still a controversial subject. The authors present a new parameter µ0τ0, evaluated from steady-state transport measurements on a-Si:H layers, which can indeed relate film quality and cell performance as far as the latter is limited by the quality...

Université de Neuchâtel

Ambipolar diffusion length and photoconductivity measurements on ”midgap'' hydrogenated microcrystalline silicon

Goerlitzer, M. ; Beck, N. ; Torres, P. ; Meier, J. ; Wyrsch, Nicolas ; Shah, Arvind

In: Journal of Applied Physics, 1996, vol. 80, no. 9, p. 5111-5115

Hydrogenated microcrystalline silicon (µc-Si:H) deposited by VHF plasma-enhanced chemical vapor deposition has recently been proven to be fully stable, with respect to light-induced degradation, when adequately used in p-i-n solar cells. Stable solar cells efficiencies of 7.7% have been obtained with single-junction cells, using ``midgap'' microcrystalline i-layers, having...

Université de Neuchâtel

The “Micromorph” cell: a new way to high-efficiency-low-temperature crystalline silicon thin-film cell manufacturing?

Keppner, H. ; Kroll, U. ; Torres, P. ; Meier, J. ; Platz, R. ; Fischer, D. ; Beck, N. ; Dubail, S. ; Anna Selvan, J. A. ; Pellaton Vaucher, N. ; Goerlitzer, M. ; Ziegler, Y. ; Tscharner, R. ; Hof, Ch. ; Goetz, M. ; Pernet, P. ; Wyrsch, Nicolas ; Vuille, J. ; Cuperus, J. ; Shah, Arvind ; Pohl, J.

In: AIP Conference Proceeding, 1997, vol. 394, no. 1, p. 271-281

Hydrogenated microcrystalline Silicon (µc-Si:H) produced by the VHF-GD (Very High Frequency Glow Discharge) process can be considered to be a new base material for thin-film crystalline silicon solar cells. The most striking feature of such cells, in contrast to conventional amorphous silicon technology, is their stability under light-soaking. With respect to crystalline silicon technology,...