Non‐Polar a ‐Plane AlN Growth on Nitrided r ‐Plane Sapphire by Ga–Al Liquid‐Phase Epitaxy

Growth of non‐polar AlN layers is important to realize high‐efficiency deep‐ultraviolet light‐emitting diodes. In this study, a ‐plane AlN layers are fabricated by a combination of thermal nitridation and Ga–Al liquid‐phase epitaxy (LPE). Thermal nitridation at 1603 and 1623 K provides a ‐plane AlN thin films with smooth surfaces on r ‐plane sapphire substrates. However, these AlN films contain a double domain structure. Nitridation of r ‐plane sapphire with an off‐cut angle can effectively eliminate the double domain structure. Moreover, a ‐plane AlN films are grown homoepitaxially on the nitrided r ‐plane sapphire substrates by Ga–Al LPE. Thus, a single‐domain non‐polar AlN film is successfully grown on nitrided r ‐plane sapphire with an off‐cut angle.