Kinetics of drift current of small charge and determination of lifetime of charge carriers

Equations of the longitudinal photocurrent in a layer having arbitrary distributed trapping levels of one type and non-uniform field are solved. Expressions for the time dependence of the photocurrent in the form of formulae and curves are presented. The procedure for the determination of the dependence of the charge carrier lifetime and the field strength on the coordinate from experimental data of the drift current of a small charge is described. The lifetime of holes and electrons in selenium amorphous layers has been experimentally found to depend substantially on the manufacturing process: increasing the substrate temperature during vacuum evaporation the lifetime of charge carriers increases. As the concentration of As in amorphous As-Se layers is increased the lifetime of charge carriers rises to several ms. The lifetime of charge carriers in amorphous selenium layers has been found to increase with the distance from the layer surface. In As2Se3 layers a negative space charge is formed on applying the voltage, and the density of the charge formed substantially increased towards the anode.