Photomemory effect in Cu2O single crystals kinetics of the excitation and de-excitation processes

A theoretical analysis of the kinetics of the excitation and de-excitation processes is presented. It is based on the energy level diagram which has been proposed in a previous paper, for the interpretation of the phenomenology of the photomemory effect. A simple, although general, mathematical treatment of the problem, is given. A good agreement is found between the theoretical predictions and the experimental results. The excitation process closely satisfies the reciprocity law. The depths and the capture cross sections of traps A and B are determined by two independent methods. The first one is based on a fit between the theoretical and experimental thermal variations of the density of trapped electrons at constant heating rate; the second one uses the correlation between the temperature of the conductivity maximum and the heating rate. The nature of the trapping centres is discussed.