DANGLING BONDS AND METASTABILITY IN SEMICONDUCTORS.

All semiconductors have dangling bonds. In crystals they are found on the surface, in grain boundaries, in dislocations, in point defects, near impurities and in vacancies. In amorphous semiconductors, there is a much greater opportunity to form dangling bonds. The author reviews various major observations of metastability in a-Si:H, summarizes the main models to be tested, shows that the breaking of weak bonds model is compatible with the charge redistribution model, and presents a perspective on what remains to be done.