Light-induced creation of defects related to low energy photoluminescence in hydrogenated amorphous silicon

We have studied intensity and lifetime distribution of low energy photoluminescence (PL) in a-Si:H films containing native defects of various densities, prepared at various substrate temperatures, and those containing photo-created defects after illumination of pulsed light from a YAG–OPO laser system. A relation between the density of dangling bonds (DBs) and intensity of low energy PL is obtained for the films before illumination. The low energy PL in the films after illumination is stronger than that expected from the relation. The illumination does not cause sizable change of the lifetime distribution of the low energy PL of 0.95 eV. These results suggest a strongly inhomogeneous spatial distribution of photo-created DBs.