Controlled crystal orientations of semipolar AlN grown on an <i>m</i> -plane sapphire by MOCVD

Abstract

Abstract The way to control AlN orientations on an m -plane sapphire in metal-organic chemical vapor deposition has not been clarified. We investigated the effect of the nitridation process on the crystal orientation of semipolar AlN on an m -plane sapphire. In terms of substrate heating, (10-1-3) AlN was obtained under H 2 without NH 3 , whereas (11–22) AlN was obtained by heating with H 2 and NH 3 . Temperature-dependent nitridation demonstrated that the AlN orientation changed from (10-1-3) to (11–22) at the nitridation temperature of 500 °C, which can be explained by the formation of r -plane nanofacets on m -plane sapphire under significant nitridation at a high temperature. At a nitridation temperature of 1100 °C, a small amount of NH 3 led to the formation of (11–22) AlN, indicating that care must be taken to keep the reactor conditions for producing desired AlN orientations with reproducibility.