Abstract
A critical analysis is given of possible mechanisms of light-induced degradation in amorphous Si:H (a-Si:H) and of the constraints imposed on degradation models by recent experimental observations. Using an analogy with processes in recombination-enhanced degradation of GaAs, it is shown that current intrinsic models for a-Si:H are deficient in two significant respects. It is also found that these intrinsic models cannot explain several important observations. An alternative extrinsic model is shown to be free of these deficiencies.