Effect of hole blocking layer on V-pit hole injection and internal quantum efficiency in GaN-based yellow LED

Abstract

Five types of GaN-based yellow light-emitting diodes (LEDs) with both a V-pit and a hole blocking layer (HBL) have been investigated numerically. The simulation results show that the GaN hole blocking layer in the p region (HBLP) can not only increase the ratio of the hole current via the V-pit, but also increase the electron leakage into the p layer via the flat region, leading to the lower internal quantum efficiency (IQE). Compared to the GaN HBLP, the Al0.5Ga0.5N HBLP is helpful in suppressing the electron leakage via the flat region to the p layer; however, it increases the electron leakage via the V-pits to the p layer, resulting in an unsatisfactory improvement of IQE. In order to settle out this issue, the AlN hole blocking layer in the n region (HBLN) is designed in the sidewall of the V-pit. It is found that the HBLN can not only alleviate the electron leakage via the V-pits to the p layer, more importantly, but also block the hole leakage via the V-pits to the n layer, leading to the improvement of IQE.