Calculation of transient photocurrents in insulators with trapped space charge

Abstract

The transit times and pulse shapes of photoinjected carriers moving in the presence of trapped space charge are derived. Two distributions are considered: uniformly trapped space charge, and trapped space charge decreasing exponentially in position from the injecting electrode. The pulse shapes are in some cases similar to those arising from transient space‐charge‐limited currents. The results in the case of the exponentially trapped space charge may have application in analysis of pulses taken in the presence of space charge trapped in the excitation layer or on the surface of insulators.