Neutral and Charged Oxygen Vacancies Induce Two-Dimensional Electron Gas Near SiO2/BaTiO3 Interfaces
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- 作者：Anna V. Kimmel ; Jorge 脥帽iguez ; Markys G. Cain ; Peter V. Sushko
- 刊名：The Journal of Physical Chemistry Letters
- 出版年：2013
- 出版时间：January 17, 2013
- 年：2013
- 卷：4
- 期：2
- 页码：333-337
- 全文大小：321K
- 年卷期：v.4,no.2(January 17, 2013)
- ISSN：1948-7185
文摘
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鈥? oxygen vacancies (V2+) in the outermost TiO2 plane of the BaTiO3 and 11 nm鈥? Si鈥揙鈥揟i bonds resulting from breaking Si鈥揙鈥揝i and Ti鈥揙鈥揟i 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.