Distinguishing Optical Behavior of Oxygen States and Native Deep Level Emission in ZnTe
The introduction of oxygen in ZnTe provides an isoelectronic radiative defect that can form an intermediate band attractive for optoelectronic applications. ZnTe also exhibits native deep level emission in close spectral proximity to oxygen emission, which can obscure the understanding of these electronic states. The photoluminescence characteristics of ZnTe epitaxial layers on GaAs are studied with the intentional introduction of oxygen and native deep levels. Native deep level emission at 1.8 eV demonstrates a reduced quenching in emission at increasing temperature and dominates at room temperature. However, the overall radiative emission of oxygen states at 1.9 eV in ZnTeO is reduced in samples in which native deep level emission is present. Despite the radiative nature and weak temperature dependence of luminescence efficiency, oxygen incorporation demonstrates significantly higher radiative emission that is maximized with the reduction of the native deep level emission.