An Ab Initio Study for Oxygen Adsorption Behavior on Polar GaN Surfaces

Theoretical investigations for the adsorption behavior of O atoms on both Ga‐polar (+c) surface and N‐polar (c) GaN surfaces using ab initio calculations to clarify the influence of adsorption behavior on oxygen incorporation are presented. The calculations demonstrate that the O atom is stabilized by forming GaOH bond on the flat +c plane GaN(0001) surface, while the topmost N atom is replaced by the O atom on the flat c plane GaN(000) surface. The calculations using the nudged elastic band method also reveal that the energy barriers for oxygen incorporation on the flat c plane surface are comparable to that on the flat +c plane surface. Furthermore, the adsorption energy on the c plane surface drastically increases on the vicinal surface with step edges and kinks, indicating that step edges and kinks enhance the incorporation of O atoms on the c plane surfaces. The calculated results offer better understanding of the atom‐scale mechanisms for the orientation dependence of oxygen concentrations in GaN.