Photoluminescence and optically detected magnetic resonance of a-Si1−xCx:H films

Abstract We report on a study of c2-photoluminescence, optically detected magnetic resonance (ODMR) and the lifetime distribution from frequency resolved measurements on a-Si 1−x C x :H alloys. The data suggest that there is a major change in the recombination mechanism near x = 0.5. At low x the films behave like Si and the main effect of alloying is the flattening of the band tails and the enhancement of the defect density. Above x ≈ 0.5 the behavior is distinctly different: the PL-intensity is independent of temperature and the C-defects do not act as non-radiative recombination centers. It is suggested that in this composition range the emission occurs from isolated sp 2 -bonded clustered units.