The effect of oxygen vacancies in TiO2 on the electronic properties of Pt/TiO2/Pt heterojunctions were investigated using first-principles methods. The arrangement of oxygen vacancies in TiO2 slabs was a crucial factor for conducting filament formation. Extended defect induced by the aligned neutral oxygen vacancies results in defect states being located at the Fermi level of the Pt electrodes in Pt/TiO2/Pt heterostructures, and produces a conducting filament connecting two Pt electrodes in the TiO2 film via the oxygen-deficient Ti ions. As oxygen vacancies in intrinsic state, the O-deficient Ti ions, which remain in a high valence state, like those in perfect TiO2, did not contribute to the conducting filament formation. Electronic structure analysis suggests that metallic filament formation in Pt/TiO2/Pt resistive switching cells might be closely related to the charge state and the arrangement of oxygen vacancies in TiO2 films.

Role of Oxygen Vacancies in TiO2-Based Resistive Switches. Gu, T.: Journal of Applied Physics, 2013, 113[3], 033707