An investigation of amorphous silicon solar cells with a gettering layer

Hydrogenated amorphous silicon solar cells (a-Si:H) with a modified intrinsic layer (in this case a so called "gettering layer") show an interesting pattern of photo-degradation during long exposure to simulated sunlight. This work presents some initial results from a careful examination of the behaviour of minority carrier lifetimes and spectral responses of standard, normal cells and cells with a modified intrinsic layer at all stages throughout the photo-degradation. The observed changes in the spectral responses and minority carrier lifetimes during degradation are remarkably different in the two types of solar cells under investigation. Cells with a modified intrinsic layer seem to be more stable during all stages of prolonged photodegradation. We suspect that processes involving the formation of light induced defects and their migration inside the intrinsic layer can at least partially explain the differences in changes observed in these samples.