Université de Neuchâtel

Microcrystalline Silicon Solar Cells: Theory and Diagnostic Tools

Meillaud, Fanny ; Shah, Arvind ; Bailat, Julien ; Vallat-Sauvain, Evelyne ; Roschek, T. ; Rech, Bernd ; Dominé, Didier ; Söderström, Thomas ; Python, Martin ; Ballif, Christophe

In: Conference Record of the 2006 IEEE 4th World Conference on Photovoltaic Energy Conversion, 2006, vol. 2, p. 1572-1575

A simple theoretical model for pin/nip-type muc-Si:H solar cells is presented. It is based on a superposition of a drift-dominated collection model and of the classical drift-diffusion transport model of the pn-diode. The model is the basis for a solar cell equivalent circuit, identical to the one introduced by Merten et al., for amorphous cells. The equivalent circuit serves as framework for the...

Université de Neuchâtel

Microstructure and surface roughness of microcrystalline silicon prepared by very high frequency-glow discharge using hydrogen dilution

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

In: Journal of Non-Crystalline Solids, 2000, vol. 266-269, p. 125-130

The microstructure of a series of silicon films deposited by very high frequency glow discharge (VHF-GD) with silane concentration in hydrogen varying from 100% down to 1.25% has been observed with transmission electron microscopy (TEM). The surface topography of the layers has been analysed by atomic force microscopy (AFM). At silane concentration below 8.6%, a phase transition between amorphous...

Université de Neuchâtel

Influence of substrate on the microstructure of microcrystalline silicon layers and cells

Bailat, Julien ; Vallat-Sauvain, Evelyne ; Feitknecht, Luc ; Droz, Corinne ; Shah, Arvind

In: Journal of Non-Crystalline Solids, 2002, vol. 299-302, p. 1219-1223

Hydrogenated microcrystalline silicon i-layers were deposited with a fixed silane concentration on various substrates and incorporated into n–i–p solar cells. ‘Average crystallinity' and detailed microstructure of layers and devices were evaluated by X-ray diffraction (XRD) and transmission electron microscopy (TEM), respectively. The role of the substrate is thereby shown to be very...

Université de Neuchâtel

Effect of the microstructure on the electronic transport in hydrogenated microcrystalline silicon

Wyrsch, Nicolas ; Droz, Corinne ; Feitknecht, Luc ; Torres, Pedro ; Vallat-Sauvain, Evelyne ; Ballif, Christophe ; Shah, Arvind

In: Journal of Non-Crystalline Solids, 2002, vol. 299-302, p. 390-394

Undoped hydrogenated amorphous silicon layers deposited at different values of very high frequency (VHF) powers and silane to hydrogen dilution ratios possess various types of microstructures. Transport and defect measurements on layers suggest that structural properties (e.g., crystallite shape and size) do not significantly affect electronic properties. The latter depend mostly on defect...

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...

Université de Neuchâtel

Basic efficiency limits, recent experimental results and novel light-trapping schemes in a-Si:H, μc-Si:H and ‘micromorph tandem' solar cells

Shah, Arvind ; Vaněček, Milan ; Meier, Johannes ; Meillaud, Fanny ; Guillet, Joelle ; Fischer, Diego ; Droz, Corinne ; Niquille, Xavier ; Faÿ, Sylvie ; Vallat-Sauvain, Evelyne ; Terrazzoni-Daudrix, Vanessa ; Bailat, Julien

In: Journal of Non-Crystalline Solids, 2004, vol. 338-340, p. 639-645

Theoretical: Limits for Jsc, Voc, FF and efficiency of single-junction solar cells and tandems are derived, as a function of Eg, showing that: (1) double-junction ‘micromorph' solar cells constitute an optimum combination of bandgap values; (2) main future gain for thin-film silicon solar cells will be increasing...

Université de Neuchâtel

Relation between substrate surface morphology and microcrystalline silicon solar cell performance

Python, Martin ; Vallat-Sauvain, Evelyne ; Bailat, Julien ; Dominé, Didier ; Fesquet, Luc ; Shah, Arvind ; Ballif, Christophe

In: Journal of Non-Crystalline Solids, 2008, vol. 354, p. 19-25

In the present paper, the structural and electrical performances of microcrystalline silicon (μc-Si:H) single junction solar cells co-deposited on a series of substrates having different surface morphologies varying from V-shaped to U-shaped valleys, are analyzed. Transmission electron microscopy (TEM) is used to quantify the density of cracks within the cells deposited on the various...

Université de Neuchâtel

Microcrystalline/micromorph silicon thin-film solar cells prepared by VHF-GD technique

Meier, Johannes ; Vallat-Sauvain, Evelyne ; Dubail, S. ; Kroll, U. ; Dubail, J. ; Golay, S. ; Feitknecht, Luc ; Torres, Pedro ; Faÿ, Sylvie ; Fischer, D. ; Shah, Arvind

In: Solar Energy Materials and Solar Cells, 2001, vol. 66, no. 1-4, p. 73-84

Hydrogenated microcrystalline silicon prepared at low temperatures by the glow discharge technique is examined here with respect to its role as a new thin-film photovoltaic absorber material. XRD and TEM characterisations reveal that microcrystalline silicon is a semiconductor with a very complex morphology. Microcrystalline p–i–n cells with open-circuit voltages of up to 560–580 mV could...

Université de Neuchâtel

Microcrystalline silicon and the impact on micromorph tandem solar cells

Meier, Johannes ; Dubail, S. ; Golay, S. ; Kroll, U. ; Faÿ, Sylvie ; Vallat-Sauvain, Evelyne ; Feitknecht, Luc ; Dubail, J. ; Shah, Arvind

In: Solar Energy Materials and Solar Cells, 2002, vol. 74, no. 1-4, p. 457-467

Intrinsic microcrystalline silicon opens up new ways for silicon thin-film multi-junction solar cells, the most promising being the “micromorph” tandem concept. The microstructure of entirely microcrystalline p–i–n solar cells is investigated by transmission electron microscopy. By applying low pressure chemical vapor deposition ZnO as front TCO in p–i–n configurated micromorph...

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...