Electronic and optical properties of different concentrations of Ga doped ZnO: CASTEP study

Abstract

In this study, the electronic and optical properties of a <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$2\times 2\times 2$</tex> ZnO supercell doped with 1Ga atom (3.125 at % concentration),and 2Ga atoms (6.25 at % concentration) were investigated using Density Functional Theory (DFT). Different parameters such as band gap, density of state, dielectric function, and absorption spectra have been calculated within CASTEP code using OFTG pseudopotential. The calculated band gap and lattice constants of ZnO are consistent with results from earlier theoretical studies. The results obtained of the electronic structure demonstrate that the band gap of ZnO decrease when it is doped with Ga, where the band gap went from 0.7ev to 0.37ev. The fermi level rises into the conduction band gives Ga-doped ZnO the properties of n-type semi-conductor. The broadening of the optical absorption peaks is observed, and the imaginary part of dielectric function moves to higher energy at a Ga concentration of 3.125 at. %, while it is shifted to lower energy with a higher intensity at a Ga concentration of 6.25 at. %. Due to these properties, it is anticipated that ZnO is a good choice for different optoelectronic devices.