Large-signal photoconductivity in semiconductors

A simple formulation based on only particle conservation, continuity of occupation of imperfection levels, and continuity of free carriers, is applied to several large signal photoconductivity problems in semiconductors with isolated imperfections with discrete energy levels. The validity of the method is demonstrated by comparison with a variety of large signal predictions of the Shockley-Read recombination model. The model is then applied to several problems of interest: (1) the lifetime expected for two competing recombination centers, (2) the phenomenon of superlinearity of majority carriers encountered in two and three center models, and (3) the effect of several different trap distributions on superlinearity and the expected light intensity dependence of photoconductivity.