Because of the near perfect local satisfaction of the valence requirements of each atom, which is complemented by the positional and compositional disorder, covalently bonded amorphous alloys are intrinsic semiconductors. We describe a band model with some novel features, which successfully describes several important effects observed in these amorphous semiconducting alloys.

• Received 21 March 1969

DOI:https://doi.org/10.1103/PhysRevLett.22.1065