Université de Neuchâtel

Microcrystalline silicon and ‘micromorph’ tandem solar cells

Shah, Arvind ; Meier, J. ; Vallat-Sauvain, Evelyne ; Droz, C. ; Kroll, U. ; Wyrsch, Nicolas ; Guillet, J. ; Graf, U.

In: Thin Solid Films, 2002, vol. 403-404, p. 179-187

The case for thin-film silicon as one of the main future options for cost-effective photovoltaic solar cells is outlined. The limitations of present amorphous silicon (a-Si:H) solar cells are briefly mentioned. Hydrogenated microcrystalline silicon (μc-Si:H) deposited by PECVD (plasma-enhanced chemical vapor deposition) at low substrate temperatures (approx. 200 °C) constitutes a new and...

Université de Neuchâtel

Complete microcrystalline p-i-n solar cell—Crystalline or amorphous cell behavior?

Meier, J. ; Flückiger, R. ; Keppner, H. ; Shah, Arvind

In: Applied Physics Letters, 1994, vol. 65, no. 7, p. 860-862

Complete µc-Si:H p-i-n solar cells have been prepared by the very high frequency glow discharge method. Up to now, intrinsic µc-Si:H has never attracted much attention as a photovoltaic active material. However, an efficiency of 4.6% and remarkably high short circuit current densities of up to 21.9 mA/cm2 due to an enhanced absorption in the near-infrared could be...

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

Electrical properties and degradation kinetics of compensated hydrogenated microcrystalline silicon deposited by very high-frequency-glow discharge

Flückiger, R. ; Meier, J. ; Goetz, M. ; Shah, Arvind

In: Journal of Applied Physics, 1995, vol. 77, no. 2, p. 712-716

Microcrystalline silicon (µc-Si:H) layers deposited by the very high-frequency-glow discharge technique at a radio-frequency excitation of 70 MHz are observed to be basically slightly n type. By doping (so-called ``microdoping'') with boron in the gas phase volume part per million (vppm) range, compensated material could be obtained. The influence of this doping on the electronic...

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

Hydrogen in amorphous and microcrystalline silicon films prepared by hydrogen dilution

Kroll, U. ; Meier, J. ; Shah, Arvind ; Mikhailov, S. ; Weber, J.

In: Journal of Applied Physics, 1996, vol. 80, no. 9, p. 4971-4975

Hydrogen incorporation in silicon layers prepared by plasma-enhanced chemical-vapor deposition using silane dilution by hydrogen has been studied by infrared spectroscopy (IR) and elastic recoil detection analysis (ERDA). The large range of silane dilution investigated can be divided into an amorphous and a microcrystalline zone. These two zones are separated by a narrow transition zone at a...

Université de Neuchâtel

Evolution of the microstructure in microcrystalline silicon prepared by very high frequency glow-discharge using hydrogen dilution

Vallat-Sauvain, Evelyne ; Kroll, U. ; Meier, J. ; Shah, Arvind ; Pohl, J.

In: Journal of Applied Physics, 2000, vol. 87, no. 6, p. 3137-3142

A series of samples was deposited by very high frequency glow discharge in a plasma of silane diluted in hydrogen in concentrations SiH4/(SiH4 + H2) varying from 100% to 1.25%. For silane concentrations below 8.4%, a phase transition between amorphous and microcrystalline silicon occurs. Microcrystalline silicon has been characterized by transmission electron...

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

Origins of atmospheric contamination in amorphous silicon prepared by very high frequency (70 MHz) glow discharge

Kroll, U. ; Meier, J. ; Keppner, H. ; Shah, Arvind ; Littlewood, S. D. ; Kelly, I. E. ; Giannoulès, P.

In: Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films, 1995, vol. 13, no. 6, p. 2742-2746

The authors have studied the effect of plasma power, reactor outgassing rates, and of silane purity on the oxygen, carbon, and nitrogen contents of amorphous silicon material prepared by the very high frequency (70 MHz) glow discharge technique. The silane purity could be optionally enhanced by the application of a getter-based silane gas purifier. It was found that oxygen incorporation was...