Computational study of oxygen stability in vicinal m(10-10)-GaN growth by MOVPE

Using density functional calculations, we clarify the oxygen incorporation mechanism in vicinal m-GaN growth by metal-organic vapor-phase epitaxy. We first identify reconstructed structures of 5 degrees off m-GaN toward the c directions. Next, we explore preferable sites for oxygen substitution near step edges. We find that oxygen prefers the lower nitrogen site of the step edge on the +c 5 degrees off m-GaN substrate compared with that on the -c 5 degrees off m-GaN substrate. This tendency agrees with recent experimental findings that the oxygen concentration in -c 5 degrees off m-GaN epilayers is lower than that in +c 5 degrees off m-GaN epilayers.