Neutral and Charged Oxygen Vacancies Induce Two-Dimensional Electron Gas Near SiO2/BaTiO3 Interfaces.
Neutral and Charged Oxygen Vacancies Induce Two-Dimensional Electron Gas Near SiO2/BaTiO3 Interfaces.
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DOI：
10.1021/jz301948k
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发表时间：
2013-01
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影响因子：
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通讯作者：
A. Kimmel;J. Íñiguez;M. Cain;P. Sushko
中科院分区：
文献类型：
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作者：
A. Kimmel;J. Íñiguez;M. Cain;P. Sushko
使用从头算分子动力学构建了 SiO2/BaTiO3 界面的原子模型。对其结构和电子性质的分析表明，（i）化学计量的SiO2/BaTiO3界面的带隙明显小于块体BaTiO3和SiO2的带隙，并且（ii）该界面在BaTiO3最外层的TiO2平面中包含~5.5 nm(-2)氧空位（V(2+)）以及由于Si-O-Si和Ti-O-Ti键断裂而产生的~11 nm(-2) Si-O-Ti键以及随后的原子重排。这种结构产生了界面极性区域，正电荷和负电荷分别位于界面的 BaTiO3 和 SiO2 部分。我们认为，在 BaTiO3 的 SiO2 涂层纳米颗粒中实验观察到的高介电响应是由于缺氧 BaTiO3 中形成的电子气且位于极性界面附近。
An atomistic model of the SiO2/BaTiO3 interface was constructed using ab initio molecular dynamics. Analysis of its structure and electronic properties reveals that (i) the band gap at the stoichiometric SiO2/BaTiO3 interface is significantly smaller than those of the bulk BaTiO3 and SiO2, and (ii) the interface contains ∼5.5 nm(-2) oxygen vacancies (V(2+)) in the outermost TiO2 plane of the BaTiO3 and ∼11 nm(-2) Si-O-Ti bonds resulting from breaking Si-O-Si and Ti-O-Ti bonds and subsequent rearrangement of the atoms. This structure gives rise to the interface polar region with positive and negative charges localized in the BaTiO3 and SiO2 parts of the interface, respectively. We propose that high dielectric response, observed experimentally in the SiO2-coated nanoparticles of BaTiO3, is due to the electron gas formed in oxygen-deficient BaTiO3 and localized in the vicinity of the polar interface.