Theoretical studies on oxygen vacancy migration energy barrier in the orthorhombic λ phase Ta2O5

Abstract Although controversy over the crystal structure of Ta2O5 has been resolved by the recently discovered energetically favorable orthorhombic λ phase model, the studies on its material properties are in the beginning stage. Among such topics, the migration energy barrier of oxygen vacancy, despite its importance especially in the device applications, has not yet been reported yet. In this study, we theoretically find out how much energy is needed for oxygen vacancies to migrate from lattice site to site in the orthorhombic λ phase Ta2O5 using the first principles calculation methods. From the results, we find that oxygen vacancies tend to be positively charged and its migration is mainly determined by the barrier in the inter-layer to intra-layer path of which validity is confirmed by the experimental measurement of oxygen diffusion characteristics.