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 photo-degradation. 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.