High-performance InGaN/GaN MQW LEDs with Al-doped ZnO transparent conductive layers grown by MOCVD using H_2O as an oxidizer

In this study, the high performance of InGaN/GaN multiple quantum well light-emitting diodes (LEDs) with Al-doped ZnO (AZO) transparent conductive layers (TCLs) has been demonstrated. The AZO-TCLs were fabricated on the n⁺-InGaN contact layer by metal organic chemical vapor deposition (MOCVD) using H₂O as an oxidizer at temperatures as low as 400℃ without any post-deposition annealing. It shows a high transparency (98%), low resistivity (510^-4 Ω·cm), and an epitaxial-like excellent interface on p-GaN with an n⁺-InGaN contact layer. A forward voltage of 2.82 V@20 mA was obtained. Most importantly, the power efficiencies can be markedly improved by 53.8%@20 mA current injection and 39.6%@350 mA current injection compared with conventional LEDs with indium tin oxide TCL (LED-Ⅲ), and by 28.8%@20 mA current injection and 4.92%@350 mA current injection compared with LEDs with AZO-TCL prepared by MOCVD using O₂ as an oxidizer (LED-Ⅱ), respectively. The results indicate that the AZO-TCL grown by MOCVD using H₂O as an oxidizer is a promising TCL for a low-cost and high-efficiency GaN-based LED application.