Optical characterization of periodically polarity-inverted ZnO structures on (0001) Al2O3 substrates

Abstract We investigated the optical properties of periodically polarity-inverted (PPI) ZnO structures formed on (0001) Al 2 O 3 substrates by evaluating the cathodoluminescence (CL) as a function of the acceleration voltage ( V acc ). At surface regions with a low V acc , the emission from the interface region was dominant but the dominant emission source changed to the Zn-polar regions as V acc was increased, which can be explained by the different exciton diffusion lengths. The dependence of the emission properties on V acc showed a slight red shift as V acc increased and a larger red shift was observed in the Zn-polar regions. Moreover, the interface regions showed the highest intensity compared to other regions, which can be explained by the results of the geometrical analysis conducted using a finite-differential time domain simulation.