The role of oxygen vacancies in the electronic and optical properties of κ-Ga2O3

Oxygen vacancies are regarded as crucial defects greatly affecting the electronic and optical properties of oxide films and devices, yet systematic studies on κ-Ga2O3 are still lacking. Herein, we investigate the thermodynamic, electronic, and optical properties of oxygen vacancies in κ-Ga2O3 using density functional theory calculations with the hybrid functional. The electronic structure reveals that oxygen vacancies create a deep donor defect in the bandgap, with defect levels and transition energies influenced by Ga atom displacement and localized electron dynamics. This interplay explains the stability of vacancies at specific sites and their connection to experimentally observed defect levels. Additionally, oxygen vacancies generate distinct absorption and electron energy loss peaks in the ultraviolet range. Our results elucidate the nature of oxygen vacancies, and offering a foundation for tuning and optimizing the electrical and optical properties of κ-Ga2O3 films and improving device performance through defect engineering. Oxygen vacancies significantly influence the electronic and optical properties of oxide films, affecting the performance of photodetectors and power devices. However, their role in metastable materials such as κ-Ga2O3 remains underexplored. In this study, we apply hybrid density functional theory to investigate the thermodynamic, electronic, and optical properties of oxygen vacancies in κ-Ga2O3, revealing that they create a deep donor defect in the bandgap, which in turn affects both defect levels and optical transition energies due to Ga displacement