First-Principle Calculation On The Electronic And Optical Properties Of ZnO Under The Loading

In this paper, the dependence of the density of the states, the band structure and the optical properties for ZnO (zinc oxide) on the loading have been studied using the CASTEP simulation software, which is based on the plane wave basis set and ultrasoft pseudopotential in the first-principle calculations.The investigation of the ZnO polymorphs under the hydrostatic pressure indicates that, the d electron states is mainly related to the atomic coordination, d electron states move to the lower energy with the increasing of the hydrostatic pressure, but the variation reduces with the increasing of the atomic coordination, it is also found that p-d repulsion and hybridization lower the variation of the band gap. The double metallic regions of the NaCl structure changes only one in the high energy range with the increasing of the pressure.With the increasing of the uniaxial stress, the band gap energy increases. The absolute values of the crystal-field splitting energy are minimum at 2 GPa for the free uniaxial stress. The restricted uniaxial stress pricks up the splitting of the valence band, but the direct-band gap does not change. For the anisotropy of wurtzite ZnO, the optical response peaks move to the higher energy with the increasing of the uniaxial stress when the polarization is along [100] direction, but the intensity of the optical response peaks changes only a little bit. But the intensity of the optical response peaks changes markedly when the polarization is along [001] direction. And the change of the starting point of the optical response is the most notable, which mainly origins from the altering of the valence band under the uniaxial stress.The stress induced by the N-doped decreases the in-plane lattice constants, but the c-axis lattice constant and the band gap energy increases. The N-doped ZnO growing in the substrate on lattice constants smaller than ZnO will benefit the N solubility. With the uniaxial stress increasing on N-doped ZnO, the band gap increases linearly. Under the compression stress, the new optical peak appears.