Model of metallic filament formation and rupture in NiO for unipolar switching

The structural and electronic implications of cation and anion vacancies in NiO are assessed using density functional theory in conjunction with the local-density approximation and employing on-site Coulomb corrections within the LDA+U method. Electronic band-structure data supports the p-type semiconducting oxide character. The calculated formation energies identify the stability of charged vacancy states consistent with experimental reports. We present a microscopic model for the formation and rupture of an electrically active filament in NiO targeted to explain the unipolar switching phenomenon observed in resistive change memory devices. The formation and filament rupture processes are linked to the migration of oxygen in the oxide coupled with the oxidation/reduction process of nickel atoms.