Edge and Self-Activated Emissions in Zinc Selenide

Abstract

The photoluminescent properties of the edge emission and the self-activated emission of pure zinc selenide crystals were studied. The spectra of the edge emission at liquid helium temperature and the self-activated emission show peak shifts to lower energies with decreasing the intensity of excitation and also with time after excitation. These are conspicuous characteristics of the donor-acceptor pair recombination. The binding energies of the donor and the acceptor relevant to the edge emission were obtained from time-resolved spectra. The binding energy of the acceptor involved in the self-activated emission was determined from the thermal quenching of the luminescence. It is likely that the donor involved in the self-activated emission is shallow and closer pairs contribute to the spectrum as compared to the low temperature edge emission. The self-activated emission is excited efficiently by the host absorption and the quantum efficiencies are as high as 25% and 70% at room and liquid nitrogen temperatures, respectively.