Correlation between hot exciton luminescence and Kelvin probe force microscopy in p-type GaN

We report the observation of intense satellite lines in the emission of p-GaN excited at 325 nm. Up to six lines are observed at the high-energy wing of the 3.1 eV emission, with separations suggesting a multiple LO phonon-related effect. The observed process is interpreted as hot exciton luminescence, enhanced by potential fluctuations. Kelvin probe force microscopy was used to image the local electrical properties of these films. The results correspond well with the behaviour of the conduction band edge fluctuations revealed in the measurements of hot exciton photoluminescence.