Pulse induced photocurrents and field distributions in photoconductor-dielectric structures

Abstract

The fundamental equations governing the charge carrier dynamics following pulsed injection into a photoconductor are solved exactly (excluding diffusion and trapping) for a configuration consisting of the photoconductor and one or two dielectrics. The solutions are obtained for initial conditions of a short pulse of arbitrarily intense light absorbed close to one surface of the photoconductor. The subsequent behavior of the internal carrier density, electric field strength, and conduction current density distributions are described analytically for all times. The dependence of the results on the number of injected carriers and on the parameter α are discussed. Here α characterizes the photoconductor-dielectric structure and depends upon the relative thicknesses and dielectric constants. The behavior of the electric field inside the photoconductor is presented in a novel manner, in which the time dependence of the field at a variety of spatial locations is displayed. The internal distributions found here are used to calculate expressions for the externally measurable variables. For two special limiting cases these expressions agree with results reported elsewhere. © 1971.