Optical absorption in semiconductors within the framework of the configurational-coordinate model

Abstract

A calculation of optical absorption in amorphous semiconductors in a wide spectral region has been made on the basis of a ‘molecular’ approach. The theoretical spectral dependence of the absorption coefficient is in a good agreement with experiment. An expression giving the relationship between the slope of the Urbach tail and the parameters describing the behaviour of the optical absorption coefficient at higher photon energies, has been obtained.