High-performance type-II InGaN-ZnGeN₂-InGaN/GaN multiple quantum well blue LEDs: design and analysis

Abstract This work reports the design and performance analysis of two multiple quantum well (MQW) blue LEDs, focusing on their optical characteristics. The first LED incorporates a conventional InGaN/GaN type-I band alignment quantum well, while the second features a (InGaN-ZnGeN 2 -InGaN)/GaN type-II quantum well. Their optical output power and efficiency droop are systematically compared to evaluate performance enhancements. Using well-calibrated APSYS simulation program we obtain energy band diagram, electroluminescence spectra, carrier concentration and radiative recombination rate. The employment of InGaN-ZnGeN 2 -InGaN QWs reduces the polarization field effect which causes increasing overlapping between electron and hole wave functions thereby leading to enhanced radiative recombination events. In addition a large valence band offset in type II band alignment increases concentration of holes alongside their better confinement in the MQW active region. Using numerical analysis our proposed type II LED is found to exhibit 225.7% improvement in output power and only 2% efficiency droop in contrast to 49% in type I LED at a current of 120 mA.