First-principles Study Of Wurtzite Mg_Xzn_1-xO

Zinc oxide (ZnO) as a new generation of semiconductor material, shows the unique and excellent physical properties on the preparation of UV and deep UV devices, it has been widely attention and in-depth researched. In the aspect of theoretical research at present, researching and predicting on the properties of the materials mainly use some calculation software (such as Materials Studio, WIEN2k, VASP, PWSCF etc.). In this article, the Materials Studio Castep module is used for calculation and analysis of the electronic structure of ZnO and properties of ternary alloy MgxZn1-xO.The paper is divided into three chapters. The first chapter mainly introduces the basic structures, properties and applications of ZnO crystals, and the research status of doped ZnO. The second chapter has made the simple introduction on the basis of first principles theory-density functional theory. In the third chapter, the lattice constants, energy gap value, band structures and density of states of wurtzite ZnO were calculated after the structure optimization, and compared with the experimental and other theoretical values. In this paper, the core of the theoretical research is electronic structure and properties of doped Mg in wurtzite ZnO, it was based on the electronic structure of intrinsic wurtzite ZnO, the variation of the lattice constant and energy gap values along with Mg components of MgxZn1-xO alloys were analyzed, and the electronic band structures and the density of states for different Mg components were calculated, and obtained the reasons for the alloy energy gap increases with increasing Mg components.The main results are as the following:1. The lattice constants of wurtzite ZnO are α=3.280A, c=5.281A respectively, and energy gap is0.750eV after calculation. These are in accordance with the results of experimental and other theoretical values. Wurtzite ZnO is direct band gap semiconductor materials. The band gap of wurtzite ZnO decided by O-2p state and Zn-4s state together. These conclusions also are consistent with experiments and other theoretical conclusions.2. The most stable structure of MgxZn1-xO various Mg components were found based on the lattice structure optimization, the a-axis length in the lattice increases, while the c-axis length decreases with the concentration of Mg increasing. MgxZn1-xO alloys with different Mg concentration are direct band gap semiconductor materials. Due to the theoretical calculation values of energy gap are smaller than the experimental values, so the energy gap values have been modified, the adjusted energy gap values are consistent with experimental data. The band gap of MgxZn1-xO alloys with different Mg concentration are decided by O-2p state and Zn-4s state, and due to the Mg atom doped, the density of states of O-2p and Zn-4s are moved to high energy region, so the band gaps of MgxZn1-xO alloys increases with increasing Mg concentration.