RECOMBINATION STATISTICS INVOLVING INTER-TRAP RECOMBINATION

The usual Shockley-Read-Hall statistics is generalized to involve reco mbination between two different traps A and B in distributed non-inter acting trap-pairs. Characteristics of inter-trap (A to B) and band-to- trap recombinations are numerically surveyed as regards their dependen ce on the thermal equilibrium Fermi level, the excitation intensity an d the interaction between A and B. The inter-trap A to B recombination rate peaks if the Fermi level is near the energy level of trap A or B in the case of moderate excitation and moderate interaction. The inte r-trap recombination rate saturates at characteristic values when thes e parameters become large. We find that for strong interaction between the traps the inter-trap recombination saturates. The reason is that the recombination between the upper trap and the valence band as well as the recombination between the lower trap and the conduction band ca n then be neglected. Saturation occurs also for strong excitation sinc e then the occupation probabilities approach unity for the upper trap and zero for the lower trap.