High internal quantum efficiency and optically pumped stimulated emission in AlGaN-based UV-C multiple quantum wells

Abstract

Internal quantum efficiency (IQE) and stimulated emission properties of AlGaN-based UV-C multiple quantum wells grown on c-plane sapphire substrates were assessed using photoluminescence spectroscopy. The IQEs were estimated to be 53% at room temperature and 16% at 750 K. Furthermore, optically pumped stimulated emission was clearly observed at room temperature. The threshold excitation power densities were estimated to be 13 kW/cm2 at 10 K and 69 kW/cm2 at room temperature. The temperature dependence of the threshold excitation power density suggested that themechanism of optical gain formation changed from excitonic transition to degenerated electron-hole plasma between 200 and 250 K.