Tailoring the Optical Properties of MOCVD Grown InGaAs/InAlGaAs MQWs with GaAs Insertion‑Layer

InGaAs/InAlGaAs multiple quantum wells (MQWs) are widely adoped as the active region of near‑infrared semiconductor lasers due to their excellent optical performance and broad application prospects. In this work, we systematically investigate the effects of the thickness of a GaAs insertion layer (ISL) on the photoluminescence (PL) behavior and defect-associated carrier recombination dynamics of InGaAs/InAlGaAs MQWs. Through comprehensive structural characterization and temperature- and power-dependent PL spectroscopy, we demonstrate that a 2 nm-thick GaAs ISL provides optimal optical performance. All measured samples exhibit a distinctive S-shaped temperature evolution of the PL peak energy, a characteristic feature arising from carrier thermal redistribution among defect-induced localized states. Notably, the sample with a 2 nm GaAs ISL shows significantly suppressed localized states, accompanied by drastically improved radiative efficiency and overall crystal quality. These findings offer essential guidance for defect-aware structural design and performance optimization of InGaAs/InAlGaAs MQW heterostructures integrated with GaAs ISLs.