Effects of photogenerated carriers in GaN layers on the photoluminescence characteristics of violet light-emitting InGaN/GaN multiple quantum wells

Abstract

Two violet light-emitting InGaN/GaN multiple quantum well (MQW) structures with different GaN barrier thicknesses are investigated by the temperature-dependent photoluminescence measurements with 325 nm He–Cd laser. At low temperatures the luminescence intensity of thick-barrier MQWs is enhanced by the increased photogenerated carriers from the thicker GaN barriers, even though the polarization field in QWs is promoted. As the temperature rises, an anomalous increase of luminescence intensity is observed from 100 to 150 K for both samples. This may be ascribed to the increased nonequilibrium carriers in the InGaN QWs due to the migration of thermal carriers from p-GaN and n-GaN layers into the depletion region. Therefore, the influence of photogenerated carriers in GaN layers on the luminescence properties of InGaN/GaN MQWs should be considered carefully for the 325-nm photoluminescence system.