Growth Mechanism of N‐Polar GaN on Vicinal N‐Polar AlN Templates in Metal‐Organic Vapor Phase Epitaxy

Abstract

In this study, nitrogen‐polar (N‐polar) GaN/Al0.9Ga0.1N/aluminum nitride (AlN) structures are grown on a sapphire substrate with an offcut angle of 2.0° from the m axis using metal‐organic vapor phase epitaxy. Low‐growth temperatures of N‐polar GaN result in a shorter Ga‐migration length, and 2D GaN growth is successfully achieved. The growth temperature and V/III ratio dependence are investigated for N‐polar GaN. As a result, high‐quality and flat N‐polar GaN is successfully grown at a low temperature of 650 °C at a high V/III ratio and nonequilibrium conditions. Through X‐ray reciprocal space mapping, N‐polar GaN can be grown coherently on a N‐polar AlN template at low temperatures around 650 °C, relaxing at higher temperatures.