Localized states emission in type‐I GaAsSb/AlGaAs multiple quantum wells grown by molecular beam epitaxy

As an important candidate for novel infrared semiconductor lasers, the optical properties of GaAsSb‐based multiple quantum wells (MQWs) are crucial. The temperature‐ and excitation power‐dependent photoluminescence (PL) spectra of the GaAs0.92Sb0.08/Al0.2Ga0.8As MQWs, which were grown by molecular beam epitaxy, were investigated and are detailed in this work. Two competitive peaks were observed from 40 K to 90 K. The peak located at the low‐energy shoulder was confirmed to be localized states emission (LE) and the high‐energy side peak was confirmed to be free‐carrier emission by its temperature‐dependent emission peak position. It is observed that the LE peak exhibited a blueshift with the increase of laser excitation power, which can be ascribed to the band filling effect of localized states. Our studies have great significance for application of GaAsSb‐based MQWs in infrared semiconductor lasers. The localized states emission and free carriers emission in GaAs0.92Sb0.08/Al0.2Ga0.8As multiple quantum wells (MQWs) were confirmed by temperature‐dependent emission peak position. The characteristics of localized states were investigated in detail. A blue shift of the localized states emission was observed, which was caused by the state filling due to alloy component fluctuations. This research is of significance for the application of GaAsSb‐based MQWs in infrared semiconductor lasers.