Reduction of efficiency droop in InGaN-based UV light-emitting diodes with InAlGaN barrier

Abstract

In this study, we fabricated and compared the performance of LEDs of InGaN-based UV MQWs active region with ternary AlGaN and quaternary InAlGaN barrier layers. HRXRD and TEM measurements show the two barriers are consistent with the lattice, and smooth morphology of quaternary InAlGaN layer can be observed in AFM. The electroluminescence results indicate that the light performance of the InGaN-based UV LEDs can be enhanced effectively when the conventional LT AlGaN barrier layers are replaced by the InAlGaN barrier layers. Furthermore, simulation results show that InGaN-based UV LEDs with quaternary InAlGaN barrier exhibit higher radiative recombination rate about 62% and low efficiency droop about 13% at a high injection current. We attribute this change to a drastic improvement from increasing of carrier concentration and redistribution of carriers, because of reduction of scatterings due to better morphology in the transverse carrier transport through the InGaN/InAlGaN MQWs.