Ab initio simulation of the electronic structure of Ta2O5 crystal modifications

Ab initio simulation of the electronic structure crystalline β and δ phases of tantalum(V) oxide (Ta2O5), representing a promising dielectric material for microelectronics, has been carried out. Both ideal crystals and those with neutral oxygen vacancies in various coordination positions have been studied. The simulation has been performed using the density functional theory with hybrid functionals involving the Hartree-Fock exchange energy. This approach gives a correct description of the bandgap width: 4.1 eV for β-Ta2O5 and 3.1 eV for δ-Ta2O5. The energy levels related to oxygen vacancies in various positions have been determined for the spectra of electron states in β- and δ-Ta2O5 polymorphs. It is established that the presence of oxygen vacancies in Ta2O5 crystal modifications leads to the formation of characteristic absorption peaks in their electron energy loss spectra