Recombination within Disordered Regions: Influence of Barrier Height on Recombination Rate and Injection Level Effects

Disordered regions are highly effective for recombination in neutron-irradiated silicon and germanium. Extension of an earlier analysis is presented which takes into account the effect of recombination on the local carrier concentration, and qualitatively explains various experimental observations, particularly the variation of lifetime with excess density. Comparisons to Gregory's impact model are made, and arguments are presented which favor the present analysis. It is observed that the previous conclusion that impurities are unimportant for recombination in neutron-irradiated material may not be valid for practical situations which involve high excess carrier densities.