Room temperature red light photoluminescence from AlGaAs multiple quantum well structures at very low excitation intensities

Abstract

Red light (700 nm) photoluminescence (PL) was obtained from two AlGaAs multiple quantum well (MQW) structures having 10 nm Al0.22Ga0.78As wells and 5 nm Al0.52Ga0.48As barriers. One sample was undoped and the other was Be doped (p=1×1018 cm−3) in the QWs. The p-doped sample emitted strong PL at low excitation intensities (<0.08 W/cm2) where the undoped sample no longer emitted detectable light. Furthermore, the p-doped sample exhibited room temperature red light emission, easily detectable to the naked eye, when illuminated by white light sources such as a flashlight or microscope light. Excitation-intensity-dependent measurements showed that the undoped sample’s PL intensity increased nearly quadratically while the doped sample’s PL intensity increased nearly linearly with increasing excitation intensity up to about 2 W/cm2. At higher excitation intensities, the luminescence intensities of both samples exhibited the same superlinear dependence; the undoped sample had about 30% higher luminescence intensity.