Université de Neuchâtel

Intrinsic microcrystalline silicon (μc-Si:H) deposited by VHF-GD (very high frequency-glow discharge): a new material for photovoltaics and optoelectronics

Shah, Arvind ; Vallat-Sauvain, Evelyne ; Torres, P. ; Meier, Johannes ; Kroll, U. ; Hof, Ch. ; Droz, C. ; Goerlitzer, M. ; Wyrsch, Nicolas ; Vaněček, M.

In: Materials Science and Engineering B, 2000, vol. 69-70, p. 219-226

The development of μc-Si:H technology and the introduction of intrinsic μc-Si:H as photovotaically active material is retraced. Special emphasis is laid on the use of very high frequency glow discharge as a particularly propitious deposition method for μc-Si:H. Thereby, the use of a gas purifier to reduce oxygen content and obtain intrinsic layers with ‘midgap’ character is described....

Université de Neuchâtel

Analysis of the inner collection efficiency in hybrid silicon solar cells

Nubile, P. ; Torres, P. ; Hof, Ch. ; Fischer, D.

In: Solid-State Electronics, 1997, vol. 41, no. 8, p. 1202-1206

The collection of photogenerated carriers in hybrid silicon solar cells structures were determined by the DICE (dynamic inner collection efficiency) technique. The hybrid solar cells have a microcrystalline n-type emitter and a crystalline p-type base. Cells with amorphous buffers of several thickness and p+ back surface field microcrystalline layers were also...

Université de Neuchâtel

Device grade microcrystalline silicon owing to reduced oxygen contamination

Torres, P. ; Meier, J. ; Flückiger, R. ; Kroll, U. ; Anna Selvan, J. A. ; Keppner, H. ; Shah, Arvind ; Littlewood, S. D. ; Kelly, I. E. ; Giannoulès, P.

In: Applied Physics Letters, 1996, vol. 69, no. 10, p. 1373-1375

As-deposited undoped microcrystalline silicon (µc-Si:H) has in general a pronounced n-type behavior. Such a material is therefore often not appropriate for use in devices, such as p-i-n diodes, as an active, absorbing i layer or as channel material for thin-film transistors. In recent work, on p-i-n solar cells, this disturbing n-type character had been...

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

Optical absorption and light scattering in microcrystalline silicon thin films and solar cells

Poruba, A. ; Fejfar, A. ; Remeš, Z. ; Špringer, J. ; Vaněček, M. ; Kočka, J. ; Meier, J. ; Torres, P. ; Shah, Arvind

In: Journal of Applied Physics, 2000, vol. 88, no. 1, p. 148-160

Optical characterization methods were applied to a series of microcrystalline silicon thin films and solar cells deposited by the very high frequency glow discharge technique. Bulk and surface light scattering effects were analyzed. A detailed theory for evaluation of the optical absorption coefficient α from transmittance, reflectance and absorptance (with the help of constant photocurrent...

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,...

Université de Neuchâtel

Integrated solar panel antennas

Vaccaro, S. ; Torres, P. ; Mosig, J. R. ; Shah, Arvind ; Zürcher,, J.-F. ; Skrivervik, A. K. ; Gardiol, F. ; de Maagt, P. ; Gerlach, L.

In: Electronics Letters, 2000, vol. 36, no. 5, p. 390-391

A new antenna which combines solar cells and printed patches is presented. The antenna is designed so as to accommodate the solar cells that provide power to an MMIC amplifier. A 2×4 array is presented, which operates at the frequency of 3.76 GHz and has a bandwidth of 16% and gain up to 30 dBi (active).

Université de Neuchâtel

Microcrystalline silicon and micromorph tandem solar cells

Keppner, H. ; Meier, Johannes ; Torres, P. ; Fischer, D. ; Shah, A.

In: Applied Physics A: Materials Science & Processing, 1999, vol. 69, no. 2, p. 169-177

“Micromorph” tandem solar cells consisting of a microcrystalline silicon bottom cell and an amorphous silicon top cell are considered as one of the most promising new thin-film silicon solar-cell concepts. Their promise lies in the hope of simultaneously achieving high conversion efficiencies at relatively low manufacturing costs. The concept was introduced by IMT Neuchâtel, based on the...

Université de Neuchâtel

Fast deposition of μc-Si:H by restrictive dilution and enhanced HF-power

Torres, P. ; Keppner, H. ; Meier, Johannes ; Kroll, U. ; Beck, N. ; Shah, A.

In: Physica status solidi. A. Applied research, 1997, vol. 163, no. 2, p. R9-R10

The purpose of this paper is to demonstrate that an enhanced deposition rate in excess of 10Å/s with reasonnable cell performances is however, indeed possible while remaining within the Very High Frequency-Glow Discharge (VHF-GD) deposition technique (at plasma excitation frequencies of 70 to 130MHz).