LAUSR

Abstract Zinc oxide is regarded as a third generation transparent conductive film which can replace indium doped tin oxide. It can be widely used in the electrodes of solar cells, the display of electronic instruments and other devices. In this paper, the photoelectric properties of ZnO thin films and their different growth directions were studied, and the best growth direction was obtained. The ZnO system was calculated by density functional theory. The band structure, density of states and other electronic properties of the stable structure are calculated by using Quantum Espresso program. It is found that the Valence Band Maximum and Conduction Band Minimum of ZnO (002) crystal plane both pass through the Fermi level, and the system exhibits semi-metallic properties, which has an important effect on the electrical properties. The band structure is interpolated by wannier90 program, and the precise maximum localized Wannier functions are obtained. Phonons properties are studied by density functional perturbation theory, and the accurate phonon dynamic matrix and the electron phonon coupling matrix elements are obtained. Based on that, the Perturbo program is used to solve the Boltzmann Transport Equation by using relaxation time approximation and electron phonon coupling theory. The scattering rate and relaxation time under different temperature are obtained and the reason why the conductivity and mobility decrease with the increase of temperature is analyzed. In the optical properties of the calculation, the time-dependent density functional theory and epsilon.x program are used to solve the Kohn–Sham equation, and then find out the refractive index, absorption coefficient, visible light transmittance and other important optical properties by obtaining the dielectric function. Combined with the analysis of electrical and optical properties, the (002) crystal plane is determined to be the best growth direction, which is well consistent with the preferred orientation obtained from the experiment. Therefore, it provides a theoretical basis and support for the preparation of better ZnO thin films. The work in this paper fills the blank of theoretical research on ZnO.