Convergence of the formation energies of intrinsic point defects in wurtzite ZnO:first-principles study by projector augmented wave method

Abstract

Electronic structure, formation energies, transition levels, and concentration of intrinsicdefects in wurtzite ZnO are investigated by the projector augmented wave method in thegeneralized gradient approximation. Interstitials, vacancies, and antisites at differentcharge states are considered. Convergence of the formation energies of variousintrinsic point defects is carefully checked, and comparison with earlier resultsis made and discussed. Even though there exists a difference for the calculatedformation energies of certain defects, our calculations also show that oxygen and zincvacancies are the dominant intrinsic donor and acceptor defects in ZnO, indicatinga consistency among results by different methods. The oxygen vacancy is notexpected to be the main source of strong n-type conductivity in the unintentionallydoped ZnO, due to its deep level in the bandgap, but it must be the origin of theexperimentally observed visible photoluminescence band centred between 2.3 and 2.5 eV.