中国物理B ›› 2008, Vol. 17 ›› Issue (2): 655-661.doi: 10.1088/1674-1056/17/2/049

• CONDENSED MATTER: STRUCTURAL, MECHANICAL, AND THERMAL PROPERTIES • 上一篇    下一篇

Ab initio study of oxygen-vacancy LaAlO2(001) surface

唐金龙, 朱 俊, 秦文峰, 熊 杰, 李言荣   

  1. State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054, China
  • 收稿日期:2007-03-08 修回日期:2007-09-04 出版日期:2008-02-20 发布日期:2008-02-20
  • 基金资助:
    Project supported by the National Science Fund for distinguished Young Scholars of China (Grant No 50425207).

Ab initio study of oxygen-vacancy LaAlO2(001) surface

Tang Jin-Long(唐金龙), Zhu Jun(朱俊)†, Qin Wen-Feng(秦文峰),Xiong Jie(熊杰), and Li Yan-Rong(李言荣)   

  1. State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054, China
  • Received:2007-03-08 Revised:2007-09-04 Online:2008-02-20 Published:2008-02-20
  • Supported by:
    Project supported by the National Science Fund for distinguished Young Scholars of China (Grant No 50425207).

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摘要： Density functional theory is used to investigate the surface structures and the energies of two possible terminated LaAlO$_{3}$ (001) surfaces with oxygen vacancies, i.e. LaO- and AlO$_{2}$-terminated surfaces. The large displacements of ions, deviated from their crystalline sites, can lead to the formation of the surface rumpling. From thermodynamics analysis, the AlO$_{2}$-terminated surface with oxygen-vacancies is less stable than the LaO-terminated one. Some states in the gap lie under the Fermi level by about --1eV in the LaO-terminated surface with oxygen vacancies. For the AlO$_{2}$-terminated oxygen-vacancy surface, some O 2p states move into the mid-gap region and become partially unoccupied. The two types of termination surfaces exhibit conduction related to oxygen vacancies. Our results can contribute to the application of LAO films to high dielectric constant materials.

Abstract: Density functional theory is used to investigate the surface structures and the energies of two possible terminated LaAlO$_{3}$ (001) surfaces with oxygen vacancies, i.e. LaO- and AlO$_{2}$-terminated surfaces. The large displacements of ions, deviated from their crystalline sites, can lead to the formation of the surface rumpling. From thermodynamics analysis, the AlO$_{2}$-terminated surface with oxygen-vacancies is less stable than the LaO-terminated one. Some states in the gap lie under the Fermi level by about --1eV in the LaO-terminated surface with oxygen vacancies. For the AlO$_{2}$-terminated oxygen-vacancy surface, some O 2p states move into the mid-gap region and become partially unoccupied. The two types of termination surfaces exhibit conduction related to oxygen vacancies. Our results can contribute to the application of LAO films to high dielectric constant materials.

Key words: oxygen vacancy, surface conduction, density functional calculation

中图分类号:  (Surface states, band structure, electron density of states)

  • 73.20.At
68.35.B- (Structure of clean surfaces (and surface reconstruction)) 61.72.J- (Point defects and defect clusters) 73.20.Hb (Impurity and defect levels; energy states of adsorbed species) 71.15.Mb (Density functional theory, local density approximation, gradient and other corrections) 68.35.Md (Surface thermodynamics, surface energies)