First-principles Calculations Of Doped Zno

The property of wurtzite structure is stabe and common in the structure of ZnO, which is a new type of direct band gap oxide semiconductor materials, the case of Ⅱ-Ⅵ, have some superior value.in photovoltaic and piezoelectric, Under the general gradient approximation (GGA), the band structure, electronic density of states, and charge density, Absorption, Dielectric function, Reflectivity and Loss function of wurtzite supercell structure (2x2x2) ZnO have been investigated by the first-principles calculation based upon density functional theory The results showed that: the band gap is0.809eV, The conduction band is mainly provided by the Zn atoms, the valence band is mainly provided by the Zn and O, due to the optical transitions between the Zn and O, making ZnO has three absorption peaks. The corresponding energy is3.0eV,8.0eV,11.3eV,There is an absorption edge in the UV-visible region near0.8eV corresponds to the luminescence radiation electrons from the conduction band to valence band transitions. Othe optical properties in accordance with experimental value。Under the general gradient approximation (GGA), electronic structure and optical properties of Mg doped ZnO have been investigated by the first-principles calculation based upon density functional theory, electronic structure include the band structure, electronic density of states and charge density The calculated results show that the substitution of Zn atom by Mg induce obvious changes in the electronic structure of ZnO. The Absorption and Dielectric function changes with the variation of the concentration of Mg atoms in the high and low energy ranges since the electronic distribution of Mg atom is different from that of the Zn atoms. At the same time,the Reflectivity and Loss function have same changes.The band gap increases and the absorption edge exhibits a blue shift when the concentration of Mg atoms increases in the Mg doped ZnO. Some new absorption and Dielectric function peaks are observed in the high energy region. Moreover the doping not only changes the intensity of the optical properties, have a certain impact on the energy level spacing.Under the general gradient approximation (GGA), the lattice parameters, the band structure, electronic density of states, charge density and optical properties of Na doped ZnO have been investigated by the first-principles calculation. The calculated results show that the substitution of Zn atom by Na increases the carrier concentration effectively. New impurity band will be appeared near the Fermi level, which is provided by the Na-2p through the analysis of density of states, and make it become a possible for p type ZnO. The study also found that:relative to not doping ZnO, Optical properties of Na-doped ZnO have some changes in the low energy region, a new absorption peak and the dielectric peak in the low energy region, the absorption of doped ZnO for ultraviolet light increase apparently,and there is almost no changes in the high energy region.these changes are due to the electronic structure changes...