Study On Electronic Structure And Properties Of Ba-doped ZnO

In this paper,using first-principles method based on density functional theory to calculate the electronic structure,ferroelectric properties,and optical properties of zinc oxide doped Ba and Ba-doped zinc oxides nanostructures(including ZnO thin films,ZnO nanotubes,and ZnO nanowires).Caculations proves that:1.The electronic structure and ferroelectric properties of ZnO bulk materials and Ba-doped ZnO(Zn8-xBaxO8)materials show that:(1)ZnO bulk materials and ZnOmaterials doped with Ba atoms(Zn8-xBaxO8)are directly wide band gap semiconductor material and its band gap width increases with the number of Ba atom dopings.(2)With the increase of Ba atom doping number,the ZnO polarizability increases,but the relative dielectric value decreases.2.The electronic structure and ferroelectric properties of ZnO thin films and Ba-doped ZnO thin films(Zn5-xBa5O5 films)show that:(1)ZnO thin films and Ba-doped ZnO thin films(Zn5-xBa5O5 films)are not directly for wide band gap semiconductor materials,the forbidden band width of ZnO films first decreases and then increases with the increase in the number of Ba atoms doped.(2)Compared with pure ZnO films,the z-axis polarizability and relative dielectric constant of ZnO films doped with Ba atoms increase first and then decrease with increasing doping number.3.The electronic structure,optical properties and ferroelectric properties of ZnO nanotubes and ZnO nanotubes doped with Ba atoms(Zn18-x,Ba,O18 nano-tube)show that:(1)The ZnO nano-tube and Zn18-xBaxO18 doped with Ba atoms(Zn18-xBaxO18 nano-tube)are all direct wide band-gap semiconductor material and the forbidden band width of ZnO nanotubes first increases and then decreases with the increase of the number of Ba atom doping;(2)The polarization on the x,y,and z axes of ZnO nanowires increases with the increase in the number of doped Ba atoms.However,the relative value is decreasing.(3)The reflectance gradually increases in the visible light region,and the absorption edge moves slightly toward the high energy direction,that is,there is a similar "blue shift" phenomenon at the nanometer scale.4.The electronic structure,optical properties and ferroelectric properties of ZnO nanowires and ZnO nano wires doped with Ba atoms(Zn6-x,Bax,O6 nano-wires)show that:(1)Band gaps of ZnO nanowires The value increases first and then decreases with increasing number of Ba atom doping.(2)The polarization on the x,y,and z axes of ZnO nanowires increases with the increase in the number of doped Ba atoms.However,the relative value is decreasing.(3)The reflectance gradually increases in the visible light region,and the absorption edge moves slightly toward the high energy direction,namely,there is a so called "blue shift" phenomenon in the ZnO nano-wires.