Suppression of hole leakage by increasing thickness of the first AlGaN barrier layer for GaN/AlGaN ultraviolet light-emitting diode

Abstract

The influence of thickness of the first AlGaN barrier layer, which is closest to the n-type GaN layer, on the luminescence characteristics of ultraviolet GaN/AlGaN multiple-quantum-well (MQW) light-emitting diodes (LEDs) is investigated numerically. It is found that the luminescence efficiency of LED is enhanced as the thickness of first AlGaN barrier increases. According to the energy band structures and carrier distributions in the MQW active region, it is found that the hole leakage can be suppressed by the thicker first barrier, which may be ascribed to the increased width and height of the triangular potential barrier induced by the polarization electric field in the first AlGaN barrier layer. Therefore, the concentration of holes in the whole MQW active region is increased, which improves the luminescence efficiency of the ultraviolet LEDs with thick AlGaN first barrier layer.