Optical matrix elements and cross sections for deep levels in GaAs: the impurity superlattice model

Abstract

The theory of a new method of calculating optical matrix elements for deep levels in semiconductors utilising a lattice of delta -function impurity potentials is presented. The method is applied to gallium arsenide and the results thus obtained for the photoionisation cross section are shown to be in encouraging agreement with experiment. The calculations demonstrate clearly the change in the impurity state with increasing binding energy and the importance of the higher minima in the conduction to photoionisation.