Wurtzite AlN(0001) Surface Oxidation: Hints from Ab Initio Calculations Zhi Fang Enhui Wang Yafeng Chen Xinmei Hou Kuo-Chih Chou Weiyou Yang Junhong Chen Minghui Shang 10.1021/acsami.8b08242.s001 https://acs.figshare.com/articles/journal_contribution/Wurtzite_AlN_0001_Surface_Oxidation_Hints_from_Ab_Initio_Calculations/7029311 With superior electrical and thermal properties, aluminum nitride (AlN) exhibits wide application. However, AlN is rather oxygen-sensitive and tends to be oxidized at high temperature. The surface oxidation of AlN remains a major challenge, while the underlying physics of AlN surface oxidation is still elusive. Here, First-principles calculations were performed to study wurtzite AlN(0001) surface oxidation process. The adsorption energy of oxygen was calculated to be site-dependent on the surface with varying O coverage. Calculation indicates that oxygen atoms are preferentially adsorbed at the hollow site (H3) of the AlN(0001) surface regardless of the O coverage. N<sub>2</sub> is determined as the dominant gas product. The procedure of N<sup>3–</sup> removal and the formation of N vacancies (V<sub>N</sub>) take place step by step. V<sub>N</sub> plays an accelerating role in the oxidation of AlN, and O<sup>2–</sup> prefers to occupy the site of V<sub>N</sub> via consuming the Al p lone-pair electrons and passivating the dangling bond states of Al. An O–Al–O layer is formed when the first Al–N bilayer is fully oxidized, which could be regarded as a precursor of γ-Al<sub>2</sub>O<sub>3</sub>. On the basis of our atomic-level simulation, a possible phase transformation mechanism from γ-Al<sub>2</sub>O<sub>3</sub> to α-Al<sub>2</sub>O<sub>3</sub> was further proposed. 2018-08-20 00:00:00 phase transformation mechanism Ab Initio Calculations O coverage AlN surface oxidation Al p lone-pair electrons V N γ- Al 2 O 3 α- Al 2 O 3