Investigation of structural and electronic properties of ZnO using first principle calculations

Abstract

In this research, first-principle calculations have been performed to study the geometry structure and electronic properties of ZnO. All possible exchange-correlation energy functionals were used to perform geometry optimization of ZnO in order to find the efficient calculation conditions. Bandgap energy, density of states (DOS), projected DOS (PDOS); and other properties of ZnO were also calculated and discussed. The calculated band-gap value of ZnO is less than 1.0 eV, much smaller than experimental value of 3.37 eV; while the PDOS results indicate the important roles of O 2p and Zn 3d orbitals in ZnO band structures. The well-known limitation of band-gap value calculations using Density Functional Theory (DFT) was solved by applying Hubbard potential on Zn 3d and O 2p orbitals. A full investigation with Hubbard value varying from 0.5 to 10 eV has been performed and the selected value is 8.0 eV for both Zn 3d and O 2p electrons.