Photoluminescence due to Inelastic Biexciton Scattering from an Al$_{0.61}$Ga$_{0.39}$N Ternary Alloy Epitaxial Layer at Room Temperature

The optical properties of dense excitonic systems in an Al0.61Ga0.39N ternary alloy epitaxial layer have been studied by means of photoluminescence (PL) and PL excitation spectroscopy. In addition to biexciton luminescence, the luminescence line associated with the inelastic scattering process of two biexcitons was clearly observed at room temperature, in which one of the four excitons involved was recombined radiatively leaving the other three as single excitons. The luminescence line became more prominent with increasing temperature from 4 to 300 K, which reflected the gradual thermal delocalization of biexcitons at higher temperatures.