氧空位对ZnO基(110)二维膜材料电子结构的影响研究

Study in effects of oxygen vacancy on electronic structure properties of two dimensional (110) thin film ZnO based material

在密度泛函理论方法的基础上,系统研究了本征氧化锌和氧空位氧化锌的(110)二维膜材料的形成和电子结构性质.计算分析结果表明,ZnO的本征(110)二维膜比氧空位的(110)二维膜稳定性高,ZnO的(110)二维膜有失去氧的倾向.本征ZnO的(110)膜为直接带隙型材料,带隙宽度为2.3 eV,氧空位(110)膜为间接带隙型材料,带隙宽度为1.877 eV.氧空位的(110)膜导带向下移动,并且导带中的能级简并化.氧空位(110)膜材料的导带底能级有2个能谷,分别位于1.877 eV和1.88 eV,这些位置的能级有效质量比本征膜大幅度增大,这些位置的电子速度普遍较低.ZnO的(110)膜产生氧空位之后,Zn的s电子参与形成其价带顶能级.氧空位(110)膜材料中Zn-O键的混合型结合倾向增大.

The formation and electronic structures of the intrinsic ZnO(110)film and oxygen vacant ZnO(110)film are studied by density functional theory calculation method.The results indicate that the stability of intrinsic ZnO(110)film is higher than that of the oxygen vacant ZnO(110)film,the intrinsic ZnO(110)film tends to lose oxygen.The intrinsic ZnO(110)film is direct band gap type material,the oxygen vacant ZnO(110)film is indirect band gap type material.The band gaps are 2.3 eV and 1.877 eV,respectively.The conduction band is moved to Fermi level and the bands within it tend to degenerate.There are two energy band valleys of conduction band for the oxygen vacant ZnO(110)film,they locate at 1.877 eV and 1.88 eV.The effective masses of these bands are larger than that of the intrinsic film,the electon velocity is low in general.The s electrons of Zn tend to form top valance bands for the oxygen vacant ZnO(110)film.The hybridization trend of covalence and ionic bonding is intensified.