Density Functional Theory Study On Energy Band And Density Of States Of ZnO

ZnO film has good properties of transparent conductivity,piezoelectricity, photoelectricity,gas sensibility and pressure sensibility and it's easy to implement the integration with many kinds of semiconductor material.Because of its excellent physical properties,ZnO has broad and a great deal of potential usages.The application of ZnO and the development of its relevant devices rely on the deep comprehension of the optic and electric properties of ZnO film.This paper with the title of "Density Functional Theory Study on Energy Band and Density of States of ZnO" is to further study the optic properties and electrical structure of ZnO film.This paper has important theoretic value and practical significance.The expressions about the optic properties of ZnO film are deduced using electromagnetic wave theory.The electrical structure of ZnO and its optic properties are calculated by first principles pseudo-potential approach of the plane wave based upon the density of states(DOS) using local density approximation(LDA) and ABINIT package.The transmissivity function of ZnO film is deduced in theory and its thickness,refractive index and extinction coefficient are calculated.First,the basis vectors of reciprocal lattice are determined by the basis vectors of solid state physics lattice of ZnO,therefore the first Brillouin zone is confirmed.In this region,the curves of ecut(cut off energy),acell(the size of basis vectors of primitive cell),and ngkpt(wave vector collocation) are calculated, and then the appropriate parameters are determined.On this basis,the curves of energy band and DOS of ZnO are gained.After analyzing it's known that the valence band can be basically divided into three regions,i.e.lower valence band,upper valence band and the one located in -18.1 eV with the width of 1.1 eV;the part of conduction band is mainly contributed by Zn4s,and O2p has only a little contribution in this area;ZnO is a kind of semiconductor material with a direct and wide energy band.The bottom of conduction band and the top of valence band are both in point G in the centre of Brillouin zone.The energy gap is 0.9eV,which is better than some of the computed results given by some literatures.The curves of real part and Imaginary part of complex dielectric functionε₁,ε₂, reflection spectrum R(ω)and energy loss spectroscopy L(ω)are calculated,and the physical rules are analyzed.The results required on this paper provide beneficial theoretical reference for the study on the optic properties and electric structure of ZnO film.