Oxygen vacancy defects in tantalum pentoxide: a density functional study
First principles total energy calculations were performed in order to characterize O vacancy defects in Ta2O5. A simplified version of the crystalline orthorhombic phase of Ta2O5 was used in this study. Results indicate that O vacancies in Ta2O5 can be broadly classified based on their location in the lattice. One type of vacancy (occupying the in-plane sites) displays deep or mid gap occupied states, and shallow unoccupied states, while a second type (occupying cap sites) results in shallow occupied states. For a wide range of local Fermi level or chemical potential, the neutral and +2 charged states of the in-plane type vacancy and the +2 charge state of the cap type vacancy are found to be most stable.
oxygen vacancy tantalum pentoxide defect states trap states density functional theory