Luminescence and Minority Carrier Recombination inp-Type GaP(Zn,O)

Abstract

A detailed study of luminescence and minority carrier recombination in Zn- and O-doped $p-\mathrm{G}\mathrm{a}\mathrm{P}$ is presented. To interpret the results of photoluminescence measurements, a three-path model for minority carrier recombination is developed. This model includes recombination through nearest-neighbor Zn-O complexes, isolated O donors, and an unspecified shunt path. Included in the model are the effects of thermalization of electrons trapped on Zn-O centers and the effects of plasma screening by free holes on excitons bound to these centers. These processes together with nonradiative Auger recombination of excitons and trapped electrons at Zn-O complexes provide the major limitation of the red quantum efficiency in GaP- (Zn, O). Using an iterative self-consistent fit to the available temperature and Zn-doping dependence of the red luminescence efficiency and time decay, values are obtained for all of the important capture cross sections, time decay parameters, and Auger recombination coefficients, as well as the minority carrier lifetime. In addition, the concentrations of the deep Zn-O and O centers are measured optically. It is concluded that the bulk quantum efficiency of GaP(Zn, O) can be improved by simultaneously increasing the minority carrier lifetime and decreasing the free-hole concentration (and consequent Auger processes) by compensation.