First-principles study of native point defects in ZnO

The characterization of native point defects in ZnO is still a question of debate. For example, experimental evidence for ZnO with an excess of Zn is inconclusive as to whether the dominant defects are metal interstitials or oxygen vacancies. This information is essential to understand the behavior of the material and to tailor its numerous technological applications. We use the first-principles pseudopotential method to determine the electronic structure, atomic geometry, and formation energy of native point defects in ZnO. Interstitials, vacancies, and antisites in their relevant charge states are considered and the effects of dopants are also discussed. The results show that both the Zn and O vacancies are the relevant defects in ZnO. We also propose a possible transition mechanism and defect center responsible for the experimentally observed green luminescence.