Inconsistency in the photoluminescence emission profile of ZnO when measured with different systems

When studying the photoluminescence emission profile of zinc oxide (ZnO) using laser excitation, a discrepancy is observed in the relative intensities of the exciton-related emissions and emissions associated with defects within the crystal structure, when compared to what is measured using more traditional xenon lamp excitation. To explain this disagreement, this study investigated the effect of excitation power density on the emission profile of a prepared ZnO sample using a custom-built setup. These results showed that the exciton emission has a super-linear response, while the defect emission has a linear to sub-linear response with increased excitation power density.