Optimizing InAsPSb/InAsP cladding structures to control carrier overflow and enhance emission in multiple quantum well LEDs

We fabricated III-V compound semiconductor-based LEDs using InAsSb/InAsPSb multiple quantum wells (MQWs) and investigated the effect of InAsPSb/InAsP cladding structures (doping concentration and thickness) on light emission. The LEDs were categorized into three types: MQW LED1 (the lowest doping concentration and the thinnest cladding layer), MQW LED2 (the same doping concentration and cladding thickness as LED1 but with a thicker quantum barrier (QB) than MQW LED1), and MQW LED3 (the highest doping concentration and the thickest cladding layer). Electroluminescence (EL) results showed that MQW LED3, with a higher doping concentration and a thicker cladding layer, suppressed carrier overflow and exhibited a single, stronger emission peak. In contrast, MQW LED1 and MQW LED2, with lower doping concentrations and thinner cladding layers, showed double weaker emission peaks due to carrier overflow. Temperature-dependent EL measurements indicated that MQW LED3 showed superior thermal performance, with higher activation energy, indicating better carrier confinement. Simulations revealed that optimizing the interfacial barrier height between the cladding layer and the QB is crucial for controlling carrier overflow and enhancing carrier injection. Specifically, increasing the barrier height between the InAsPSb cladding layer and the QB limits carrier overflow, while decreasing the barrier height between the InAsP and InAsPSb cladding layers improves carrier injection and increases EL intensity. These findings highlight the importance of optimizing the cladding structure to suppress carrier overflow, improve carrier recombination, and enhance the performance of III-V MQW-based optoelectronics.