Study of Efficiency Droop in InGaN-based Near-UV LEDs with Quaternary InAlGaN Barrier

Abstract

In this study, we demonstrate high efficient near-UV LEDs by replacing low-temperature AlGaN by InAlGaN barrier in active region. The efficiency droop in InGaN-based near-UV LED with AlGaN and InAlGaN barrier is investigated. High-resolution x-ray diffraction (HRXRD) and transmission electron microscopy (TEM) measurements show the two barriers are consistent with the lattice, and smooth morphology of quaternary InAlGaN layer can be observed in atomic force microscopy (AFM). Electroluminescence results indicate that the light performance of quaternary LEDs can be enhanced by 25 % and 55 % at 350 mA and 1000mA, respectively. Furthermore, simulations show that quaternary LEDs exhibit 62 % higher radiative recombination rate and low efficiency degradation of 13 % at a high injection current. We attribute this improvement to increasing of carrier concentration and more uniform redistribution of carriers.