Photoluminescence spectra of oxygen-doped ZnSe grown by molecular-beam epitaxy

Abstract

The optical properties of oxygen-doped ZnSe grown by molecular-beam epitaxy were studied by means of photoluminescence spectroscopy. Oxygen-related peaks were observed at about 4437 and at about 4550 Å, where phonon replicas also appeared. These peaks may be caused by the radiative recombination of excitons bound to neutral oxygen atoms and donor-to-oxygen-acceptor emission, respectively. Observation of donor-acceptor emission in which the acceptor is an isoelectronic acceptor is reported for the first time. Oxygen, which is an isoelectronic impurity in ZnSe, can act as an acceptor in the same way as the generally used dopants such as nitrogen. A model for the oxygen in ZnSe acting as an acceptor is proposed. The acceptor level and the effective charge of oxygen are estimated to be about 80 meV and -0.9, respectively, using the energy values of the luminescence peaks of bound-exciton and donor-acceptor emission.