The Density-of-States Tail and Interband Light Absorption

Abstract

In this chapter we describe the ``optimal fluctuation'' method, which permits one to calculate the density-of-states exponent in the forbidden gap, where the density of states is very low. We also discuss a simple modification of this method which allows to estimate the exponent using only the Poisson distribution and elementary quantum mechanics. A classification is proposed for the types of density of states which occur in doped semiconductors. The same method is then used to describe the interband light absorption.