Annihilation of frozen-in point defects in GaP by thermal and recombination-induced processes

Minority-carrier-lifetime measurements on heat-treated rapidly cooled LEC-grown GaP reveal strong nonradiative recombination at frozen-in point defects. Cathodoluminescence line scan studies show that during slow cooling the point defects introduced during heating are removed by diffusion to dislocations and microdefects; the intensity of the resulting luminescence halos around the dislocations depends on heat treatment, due to variations in minority-carrier lifetime. Alternatively, frozen-in point defects can also be annihilated by photon excitation and by electron-beam excitation. In these cases, phonons liberated during nonradiative recombination at the point defects excite defect motions which result in annihilation reactions; these are probably recombination reactions between Frenkel pairs.