Semiclassical density-of-states and optical-absorption analysis of amorphous semiconductors

A semiclassical analysis of amorphous semiconductors is presented. This analysis, cast within an effective-mass setting, provides for the overall density-of-states by averaging a local density-of-states over a distribution of potential fluctuations. Our density-of-states results span the transition from the tail states to the band states, and both analytical and numerical results are obtained. We then determine the functional form of the optical-absorption coefficient, and show that both subgap and Tauc absorption edges are captured within this analytical framework. Finally, we apply this formalism to the case of hydrogenated amorphous silicon, and find that our results are consistent with those of experiment. © 1995 The American Physical Society.