Wurtzite AlN(0001) Surface Oxidation: Hints from Ab Initio Calculations.
Wurtzite AlN(0001) Surface Oxidation: Hints from Ab Initio Calculations.
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DOI：
10.1021/acsami.8b08242
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发表时间：
2018-08
影响因子：
9.5
通讯作者：
Z. Fang;E. Wang;Yafeng Chen;X. Hou;K. Chou;Weiyou Yang;Junhong Chen;M. Shang
中科院分区：
文献类型：
--
作者：
Z. Fang;E. Wang;Yafeng Chen;X. Hou;K. Chou;Weiyou Yang;Junhong Chen;M. Shang
氮化铝（AlN）具有优异的电学和热学性能，具有广泛的应用前景。然而，AlN对氧相当敏感，在高温下容易被氧化。 AlN 的表面氧化仍然是一个重大挑战，而 AlN 表面氧化的基本物理原理仍然难以捉摸。在这里，进行第一性原理计算来研究纤锌矿 AlN(0001) 表面氧化过程。氧的吸附能被计算为取决于具有不同的 O 覆盖率的表面。计算表明，无论O覆盖率如何，氧原子都会优先吸附在AlN(0001)表面的空心位点(H3)上。 N2 被确定为主要气体产物。 N3- 的去除和 N 空位 (VN) 的形成是逐步进行的。 VN在AlN的氧化过程中起到加速作用，O2-更倾向于通过消耗Al的p孤对电子并钝化Al的悬键态来占据VN的位点。当第一个 Al-N 双层完全氧化时，形成 O-Al-O 层，可以将其视为 γ-Al2O3 的前驱体。在原子级模拟的基础上，进一步提出了从γ-Al2O3到α-Al2O3可能的相变机制。
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. N2 is determined as the dominant gas product. The procedure of N3- removal and the formation of N vacancies (VN) take place step by step. VN plays an accelerating role in the oxidation of AlN, and O2- prefers to occupy the site of VN 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-Al2O3. On the basis of our atomic-level simulation, a possible phase transformation mechanism from γ-Al2O3 to α-Al2O3 was further proposed.