Amorphous semiconductors

The research efforts of physical scientists over twenty years have helped to secure a promising commercial future for amorphous semiconductors, in areas as diverse as solar power and sub-micron optics. The authors discuss the formation and stability of amorphous solids, the atomic and electronic structures of Si and Ge, localised and extended states, defects, doping and optical properties including light-induced structural and morphological changes. A field-effect technique for measuring the localised density of states is described and related to thin-film transistor operation.