Reduction of efficiency droop for InGaN/GaN multiple quantum well light emitting diodes using AlGaN/GaN superlattice structure

Abstract

In recent years InGaN/GaN light emitting diodes (LEDs) have become a great attraction in solid state lighting due to their energy efficiency. However, these LEDs having multiple quantum well (MQW) suffer from efficiency droop. The exact cause for this droop is still not well known. But the studies show device structure and material composition play important roles in its suppression. In this simulation study the effect of inserting an AlGaN/GaN superlattice(SL) structure prior to the active region on the performance of a conventional LED have been studied through simulation. The results show that the proposed structure results in a more uniform electron concentration distribution at high injection current compared to the conventional structure. This gives rise to a better contribution to the radiative emission from different quantum wells and the internal quantum efficiency for the proposed LED structure is found to have a droop of 40% instead of 54% for the conventional LED structure.