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Université de Neuchâtel

Amorphous silicon p-i-n diodes, deposited by the VHF-GD process: new experimental results

Chabloz, P. ; Keppner, Herbert ; Fischer, Diego ; Link, D. ; Shah, Arvind

In: Journal of Non-Crystalline Solids, 1996, vol. 198-200, p. 1159-1162

a-Si:H i-layers were deposited at different substrate temperatures and plasma excitation frequencies, while the other deposition parameters were kept constant. These layers were characterised by measuring the intrinsic mechanical stress and the defect density. At deposition temperatures of 200 to 250°C low stress and a low defect density were obtained for excitation frequencies between 60 and 70...

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

The quasineutrality condition in amorphous semiconductors: Reformulation of the ‘lifetime/relaxation’ criterion

Shah, Arvind ; Hubin, J. ; Platz, R. ; Goerlitzer, M. ; Wyrsch, Nicolas

In: Journal of Non-Crystalline Solids, 1996, vol. 198-200, p. 548-551

The concepts of lifetime and relaxation semiconductors introduced by van Roosbroeck and Casey are reconsidered for amorphous semiconductors and the effect of localized states on the lifetime/relaxation criterion specified: The quantity to be considered is τρ/Td, where Td is (as before) the dielectric relaxation time, but τρ 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

Stability of a-Si:H prepared by hot-wire and glow discharge using H2 dilution evaluated by pulsed laser degradation

Hof, Ch. ; Ziegler, Y. ; Platz, R. ; Wyrsch, Nicolas ; Shah, Arvind

In: Journal of Non-Crystalline Solids, 1998, vol. 227-230, p. 287-291

The quality of intrinsic amorphous silicon films prepared by different deposition techniques was investigated. For very high frequency glow discharge, both the substrate temperature as well as the hydrogen dilution were varied. These layers were compared to hot wire material produced at comparable temperatures. To study the stability of these films, an optimised degradation method was developed...

Université de Neuchâtel

Fourier transform infrared photocurrent spectroscopy in microcrystalline silicon

Poruba, A. ; Vaněček, Milan ; Meier, Johannes ; Shah, Arvind

In: Journal of Non-Crystalline Solids, 2002, vol. 299-302, p. 375-379

Temperature and electric field dependencies of mobility and concentration transients of electrons and holes using modified charge extraction by the linearly increasing voltage (CELIV) method in slightly doped n-type, p-type and undoped microcrystalline silicon (μc-Si:H) have been investigated. The results indicates that: the mobility of majority carriers causes temperature and electric field...

Université de Neuchâtel

Simulation of the growth dynamics of amorphous and microcrystalline silicon

Bailat, Julien ; Vallat-Sauvain, Evelyne ; Vallat, A. ; Shah, Arvind

In: Journal of Non-Crystalline Solids, 2004, vol. 338-340, p. 32-36

The qualitative description of the major microstructure characteristics of microcrystalline silicon is achieved through a three-dimensional discrete dynamical growth model. The model is based on three fundamental processes that determine surface morphology: (1) random deposition of particles, (2) local relaxation and (3) desorption. In this model, the incoming particle reaching the growing...