Improvement of electroluminescent performance of n-ZnO/AlN/p-GaN light-emitting diodes by optimizing the AlN barrier layer

摘要

The effects of the growth temperature and thickness of AlN layer on the electroluminescence (EL) performance of n-ZnO/AlN/p-GaN devices have been systematically investigated. It is found that the higher growth temperature of AlN layer (T_(AlN)) may facilitate the improvement of EL performance of the device, which is attributed to that the crystalline quality of AlN layer improves with increasing growth temperatures T_(AlN). Besides the crystallinity of AlN layer, the thickness of AlN barrier layer plays an important role on the performance of the device. The thinner AlN layer is not enough to cover the whole surface of GaN, while the thicker AlN layer is unfavorable to the tunneling of carriers and many of electrons will be captured and recombined nonradiatively via the deep donors within the thick AlN layer. We have demonstrated that the AlN layer at the growth temperature of 700℃ with an optimized thickness of around 10 nm could effectively confine the injected carriers and suppress the formation of interfacial layer, thus, the EL performance of n-ZnO/AlN/p-GaN device could be significantly improved.