Influence of the crystalline fraction on the stability of nanocrystalline silicon solar cells

Recent results in nanocrystalline silicon solar cells have drawn attention to the material grown near the transition to amorphous growth, where best efficiencies have been reported. In this paper, the stability of nanocrystalline silicon solar cells deposited by Hot-Wire Chemical Vapour Deposition with relation to their microstructure is studied by means of Variable Illumination Measurement (VIM). The possible creation of light induced defects during 1000 hours of 100 mW/cm/sup 2/ light soaking has been monitored. Different amount of amorphous phase in the active layer of the device has been achieved by changing the hydrogen dilution used. After 1000 hours of light soaking, several initial irreversible changes in the performance of the solar cell have been found. Nevertheless, only the cell with the lowest crystalline fraction (X/sub c/ /spl sim/40%) suffered from reversible creation of light induced defects. This effect was not seen in other devices with X/sub c/ /spl sim/50%, where the dangling bond density was almost constant during all the light soaking process.