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