InGaN/GaN‐based green‐light‐emitting diodes with an inserted InGaN/GaN‐graded superlattice layer

Abstract

In this study, InGaN‐based green light‐emitting diodes (LEDs) with a graded‐superlattice (GSL) layer inserted between the 3 µm thick n‐type GaN and the multiple quantum wells (MQWs) were studied numerically and experimentally. The simulated results indicate that the use of GSL inserting layer consisting of 12‐stacked InGaN/GaN layers leads to the enhancement of electron injection into the MQWs resulting in the increase of radiative recombination rate, suppressing the electron overflow to the p‐GaN side. The photoluminescence and output power of the GSL LEDs show a 73.5 and 42.5%, respectively, in a comparison with the reference LEDs that has no inserting layer. This improvement with the GSL LEDs indicates that the GSL insertion layer acts not only as a stress‐relaxing buffer layer releasing the residual stress in MQWs, but also as an electron cooler enhancing the electron capture rate in MQWs.