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

摘要

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 Al_(0.5)Ga_(0.5)N 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.