Hybrid density functional study of oxygen vacancies in KTaO3 and NaTaO3
Hybrid density functional study of oxygen vacancies in KTaO3 and NaTaO3
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DOI：
10.1103/physrevb.83.214107
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发表时间：
2011-06-10
影响因子：
3.7
通讯作者：
Tanaka, Isao
中科院分区：
文献类型：
--
作者：
Choi, Minseok;Oba, Fumiyasu;Tanaka, Isao
利用Heyd-Scuseria-Ernzerhof杂化泛函系统地研究了KTaO3和NaTaO3中氧空位的能量学和电子性质。这些体系中的氧空位表现出相似的行为。在带隙内费米能级的大多数位置上，2+电荷态是最稳定的。当费米能级接近导带最小值时，中性和+电荷态的信息能量与2+电荷态相当。因此，氧空位是双浅层供体，可以提供载流子电子。两种类型的非对称构型，其中两个离氧空位最近的钽原子不对称地定位，也可能形成亚稳构型。这些亚稳构型在电子结构上表现出显著的差异；一种构型具有像稳定构型那样的离域特性，而另一种构型在带隙中诱导出深的局域状态。在预测生成能和电子性质的基础上，讨论了前人关于氧空位的实验和理论研究结果。
Using the Heyd-Scuseria-Ernzerhof hybrid functional, we systematically study the energetics and electronic properties of oxygen vacancies in KTaO3 and NaTaO3. The oxygen vacancies in these systems show similar behavior. The 2+ charge state is the most stable for most positions of the Fermi level inside the band gap. The neutral and+ charge states become comparable in formation energy with the 2+ charge state when the Fermi level is close to the conduction band minimum. Therefore, the oxygen vacancies are double shallow donors, which can provide carrier electrons. Two types of off-symmetric configurations, in which the two nearest tantalum atoms of the oxygen vacancies are asymmetrically located, also possibly form as metastable configurations. These metastable configurations show a striking difference in electronic structure from each other; one configuration has a delocalized characteristic as in the case of the stable configuration, while the other induces a deep, localized state in the band gap. On the basis of the predicted formation energies and electronic properties, the previous experimental and theoretical findings relevant to the oxygen vacancies are discussed.