Ab initio simulation of the electronic structure of δ-Ta2O5 with oxygen vacancy and comparison with experiment

Abstract

The electronic structure of a Ta2O5 insulator with oxygen vacancies is studied theoretically and experimentally. The ab initio calculations of δ-Ta2O5 are performed in terms of density functional theory using the generalized gradient (GGA) and GGA + U approximations. The electronic structure of Ta2O5 is experimentally studied by X-ray photoelectron spectroscopy (XPS). To study oxygen vacancies, an amorphous Ta2O5 film is irradiated by argon ions. The calculated XPS spectra of the valence band of δ-Ta2O5 agree satisfactorily with the corresponding experimental spectra of the amorphous films. The oxygen vacancy in δ-Ta2O5 is found to be a trap for holes and electrons. The minimum and maximum effective masses of electrons and holes in δ-Ta2O5 are calculated.