Université de Neuchâtel

Extension of the a-Si:H electronic transport model to μc-Si:H: use of the μ0τ0 product to correlate electronic transport properties and solar cell performances

Goerlitzer, M. ; Torres, Pedro ; Droz, C. ; Shah, Arvind

In: Solar Energy Materials and Solar Cells, 2000, vol. 60, no. 2, p. 195-200

The aim of this communication is to show that it is possible to extend the model of the electronic transport developed for amorphous silicon (a-Si:H) to microcrystalline silicon (μc-Si:H). By describing the electronic transport with the μ0τR products (mobility×recombination time) as a function of the Fermi level, we observed the same behaviour for both...

Université de Neuchâtel

More stable low gap a-Si:H layers deposited by PE-CVD at moderately high temperature with hydrogen dilution

Ziegler, Y. ; Daudrix, V. ; Droz, C. ; Platz, R. ; Wyrsch, Nicolas ; Shah, Arvind

In: Solar Energy Materials and Solar Cells, 2001, vol. 66, no. 1-4, p. 413-419

In the present work, several series with variation of deposition parameters such as hydrogen dilution ratio, VHF-power and plasma excitation frequency fexc have been extensively analyzed. Compared with “conventional” more-stable layers obtained at 200–250°C and high H2 dilution ratios of about 10, it was observed that electrical transport properties after...

Université de Neuchâtel

Material and solar cell research in microcrystalline silicon

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

In: Solar Energy Materials and Solar Cells, 2003, vol. 78, no. 1-4, p. 469-491

This contribution describes the introduction of hydrogenated microcrystalline silicon (μc-Si:H) as novel absorber material for thin-film silicon solar cells. Work done at IMT Neuchâtel in connection with deposition of μc-Si:H layers by very high frequency glow discharge deposition is related in detail. Corresponding layer properties w.r.t. material microstructure, hydrogen content, stability...

Université de Neuchâtel

Relationship between Raman crystallinity and open-circuit voltage in microcrystalline silicon solar cells

Droz, C. ; Vallat-Sauvain, Evelyne ; Bailat, J. ; Feitknecht, L. ; Meier, Johannes ; Shah, Arvind

In: Solar Energy Materials and Solar Cells, 2004, vol. 81, no. 1, p. 61-71

A series of nip-type microcrystalline silicon (μc-Si:H) single-junction solar cells has been studied by electrical characterisation, by transmission electron microscopy (TEM) and by Raman spectroscopy using 514 and 633 nm excitation light and both top- and bottom-illumination. Thereby, a Raman crystallinity factor indicative of crystalline volume fraction is introduced and applied to the...

Université de Neuchâtel

Efficiency limits for single-junction and tandem solar cells

Meillaud, F. ; Shah, Arvind ; Droz, C. ; Vallat-Sauvain, Evelyne ; Miazza, C.

In: Solar Energy Materials and Solar Cells, 2006, vol. 90, no. 18-19, p. 2952-2959

Basic limitations of single-junction and tandem p–n and p–i–n diodes are established from thermodynamical considerations on radiative recombination and semi-empirical considerations on the classical diode equations. These limits are compared to actual values of short-circuit current, open-circuit voltage, fill factor and efficiency for amorphous (a-Si:H) and microcrystalline (μc-Si:H)...

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

High rate growth of microcrystalline silicon by VHF-GD at high pressure

Graf, U. ; Meier, Johannes ; Kroll, U. ; Bailat, J. ; Droz, C. ; Vallat-Sauvain, Evelyne ; Shah, Arvind

In: Thin Solid Films, 2003, vol. 427, no. 1-2, p. 37-40

Microcrystalline silicon growth using very high frequency-glow discharge PECVD has been studied under conditions of high pressure and high VHF-power conditions. Hereby, the influence of the total gas flow and the silane concentration on the deposition rate has been investigated. Deposition rates of over 25 Å/s have been achieved at relatively low total gas flows of 100 sccm. These high-rate...

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

Microstructure and open-circuit voltage of n–i–p microcrystalline silicon solar cells

Bailat, J. ; Vallat-Sauvain, Evelyne ; Feitknecht, L. ; Droz, C. ; Shah, Arvind

In: Journal of Applied Physics, 2003, vol. 93, no. 9, p. 5727-5731

A series of microcrystalline silicon n–i–p solar cells has been deposited by very high frequency plasma enhanced chemical vapor deposition at various values of silane to hydrogen source gas ratio and on two different substrate types. Relationships between microstructure and electrical characteristics of these solar cells are investigated by transmission electron microscopy, atomic...