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

Long term behaviour of passively heated or cooled a-Si:H modules

Hof, Ch. ; Lüdi, M. ; Goetz, M. ; Fischer, Diego ; Shah, Arvind

In: Conference Record of the 25th IEEE Photovoltaic Specialists Conference, 1996, p. 1057-1060

We compare the outdoor performance of single junction a-Si:H PV-modules which were mounted in three different ways. One was thermally well isolated against convection and radiation losses in order to reach maximum operating temperatures. A second one was fixed onto a radiator to keep its temperature as close as possible to the air temperature. A third one served as a reference and was mounted...

Université de Neuchâtel

Amorphous silicon solar cells with graded low-level doped i-layerscharacterised by bifacial measurements

Fischer, Diego ; Wyrsch, Nicolas ; Fortmann, C.M. ; Shah, Arvind

In: Conference Record of the 23th IEEE Photovoltaic Specialists Conference, 1993, p. 878-884

Bifacial spectral response characterization of solar cells under near operating condition illumination is used in conjuncture with a novel bifacial DICE analysis to establish the collection efficiency as a function of i-layer position in p-i-n amorphous silicon solar cells. A significant portion of solar cell degradation can be explained in terms of electric field distortions which increase...

Université de Neuchâtel

Mobility, recombination kinetics, and solar cell performance

Fortmann, C.M. ; Fischer, Diego

In: Conference Record of the 23th IEEE Photovoltaic Specialists Conference, 1993, p. 966-970

In order to optimize the amorphous silicon solar cell structure for improved stabilized performance it is necessary to understand a great number of material parameters as they exist in the solar cell under operating conditions. Towards the goal of using the solar cells themselves for quantitative defect analysis, the authors show that the short wavelength quantum efficiency measurement is a means...

Université de Neuchâtel

Monitoring a-Si:H solar cells degradation by two sides blue lightcollection

Masini, G. ; Fischer, Diego ; Hubin, J. ; Palma, F. ; 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. 610-613

In view of the persistent lack of correlation between single layer material properties and solar cell performance, one is at present interested in experimental techniques which allow the characterisation of material properties within a full p-i-n cell. In this paper, the authors introduce a novel method to monitor i-layer properties during degradation of a-Si:H p-i-n solar cell. Two blue,...

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

a-Si:H/a-Si:H stacked cell from VHF-deposition in a single chamber reactor with 9% stabilized efficiency

Platz, R. ; Fischer, Diego ; Dubail, S. ; Shah, Arvind

In: Solar Energy Materials and Solar Cells, 1997, vol. 46, no. 2, p. 157-172

In the present paper we present results on a-Si:H/a-Si:H stacked cells deposited in a single-chamber reactor by the very high frequency-glow discharge (VHF-GD) deposition technique at 70 MHz. Hydrogen dilution of the i-layer yields more stable amorphous p−i−n solar cells, similar to what is observed for RF deposition. High dilution ratios of the i-layer are found to enhance contaminations....

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

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...