Theory of photoconductivity in amorphous semiconductors containing slowly-varying trap distributions

Abstract

A generalized treatment of photoconductivity in amorphous semiconductors having an M-CEO trap distribution is presented. The problem is formulated in terms of Shockley-Read recombination- generation statistics, as distinct from ad hoc formulations of previous treatments of the problem. For the first time, self-consistent characteristics are presented of photocurrent, excess hole and electron concentrations, and lifetimes as a function of light intensity and temperature, with the activation energy and energy gap as parameters. The photocurrent characteristics are found to exhibit all the salient characteristics of existing experimental data. The physics of the photoconductivity is discussed in terms of the excess carrier lifetimes and the material parameters.