Investigation of charge carrier lifetime in high-resistivity semiconductorlayers by the method of small charge photocurrent

A method of determination of charge carrier lifetime from experimental data of small charge current transient under constant electric field strength i s discussed. On the basis of experimental results on transient of small cha rge photocurrent of holes and electrons which were obtained at different el ectric field strengths, an analysis of charge carrier lifetimes in a-Se lay er has been performed. For interpretation of experimental results the appro ximation, according to which photogenerated electrons or holes can be trapp ed in levels of three types, has been used. We found that the process of lo calized charge carrier release is influenced by the electric field strength and that in a-Se layer, in the vicinity of the substrate, there is a narro w region where the density of localized states exceeds its mean in a layer. (C) 1999 Elsevier Science B.V. All rights reserved.