Abstract
As amorphous materials are characterized by atomic disorder, amorphous semiconductors have unique electrical and optical properties such as localized states, mobility edges, states in the gap arising from structural defects, variable-range hopping conduction, and optical absorption. The properties of amorphous semiconductors depend on the deposition method and its deposition conditions because amorphous materials are in non-equilibrium state. While deposition methods using neutral radical species are well known, methods using ion species are recently being considered. Since the discovery of hydrogenated amorphous silicon with structural sensitivity, a new and wide field from basic science to applications to large-area electronic devices has been opened. The basic properties, deposition methods and applications of amorphous semiconductors, particularly hydrogenated amorphous silicon are summarized.
