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

In this study, InGaN-based green light-emitting diodes (LEDs) with a graded-superlattice (GSL) layer inserted between the 3 mm 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. (C) 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim