Model of photoconduction in an amorphous medium

Abstract

A model for trap-controlled charge transport in an amorphous material is considered. The model is defined in terms of a set of coupled differential rate equations, in which each type of trap is characterized by a capture probability ${\omega }_i^{*}$ and a release probability $r_i^{*}$. This model is significant because it has recently been shown that the continuum limit of the Scher-Montroll master equation for anomalous dispersion is completely equivalent to the multiple-trapping equations. In this paper we develop the multiple-trapping model, and use asymptotic methods to treat traps whose release rates and capture rates are both different from one. We obtain an estimate of the increased transit time due to trapping, and also discuss the determination of both the number and types of different traps necessary to produce a disperse photocurrent transient.