Transient Recombination of Excess Carriers in Semiconductors

The recombination equations for a system containing an arbitrary number of Shockley-Read recombination centers are formulated. Transient solutions are obtained for the decay following the injection of a pulse of carriers into a system containing one or two centers. The specific cases considered include (1) the simple one-center case, which enables us to discuss (a) the situation for a large injection of carriers, (b) recombination through donors in $n$-type or acceptors in $p$-type material, and (c) recombination through centers in the presence of direct recombination; (2) the case of a recombination center with a temporary trap, and (3) the case of two recombination centers.