Photoluminescence in amorphous silicon

Abstract

Abstract Photoluminescence of amorphous silicon is measured in the range from 77 K to room temperature. The temperature dependence of the three bands, of which the total luminescence spectrum consists, could be determined seperately. It is found that all three of them decrease at high temperature with approximately the same activation energy of 0.13 eV. This decrease sets in at different temperatures for the different bands. The three bands are interpreted as transitions within electron‐hole pairs consisting of more or less deeply trapped carriers. The activated decrease at high temperature is explained by thermally activated dissociation of these pairs. The electron‐hole pair concept also explains why photoconductivity decreases about twice as fast as luminescence when the substrate temperature is lowered.