Excitation spectra and quantum efficiency of GaP containing Zn and O

Abstract

We have investigated the quantum efficiency for the production of red luminescence in p-type GaP doped with deep oxygen donors and shallow zinc acceptors. We find the luminescence can be efficiently excited by energy transfer from bound excitons, E2.317 eV, as well as by absorption of quanta of energy in the characteristic (phonon-assisted) absorption region h2.2 eV, and in the pair-creation region well above the band edge. The high efficiency of the exciton-induced radiation is interpreted as a resonant transfer of energy to an exciton which is weakly bound (10 meV) to an O-Zn complex and which decays to the ground (red-emitting) exciton state. The temperature dependence of the efficiency for the different excitation processes is presented and discussed and the loss in efficiency above 70°K is interpreted in terms of an Auger process involving free holes. © 1968 The American Physical Society.