The formation energy and diffusion properties of oxygen vacancy defects in λ-Ta2O5 were studied using first-principle calculations. The calculated formation energy of neutral oxygen vacancy defects was consistent with previous studies carried out, and the charged oxygen defects considering periodic correction were also studied. The calculations obtained showed that the formation energy of +2 charged oxygen vacancy defects was 0.83–1.16 eV. Also, the diffusion activation energy consisting of oxygen vacancy defect formation energy and diffusion barrier concurred well with the diffusion activation energy measured by experiments. A linear relationship was found between the diffusion barrier and the diffusion distance.

In this paper, we report our investigation of room-temperature-fabricated tungsten/indium tin oxide/gold (W/ITO/Au) resistive random access memory (RRAM), which exhibits asymmetric bipolar resistive switching (BRS) behavior. The device displays good write/erase endurance and data retention properties. The device shows complementary resistive switching (CRS) characteristics after controlling the compliance current. A WO x layer electrically formed at the W/ITO in the forming process. Mobile oxygen ions within ITO migrate toward the electrode/ITO interface and produce a semiconductor-like layer that acts as a free-carrier barrier. The CRS characteristic here can be elucidated in light of the evolution of an asymmetric free-carrier blocking layer at the electrode/ITO interface.

The formation energy of an oxygen vacancy and the diffusion barrier of an oxygen ion have a significant impact on the operating voltage and other parameters of resistive random access memory. In this research, n-type dopants and p-type dopants were, respectively, used to make comparative research on the formation energy of the oxygen vacancy and the diffusion barrier of the oxygen ion in orthorhombic λ-Ta2O5 taking first-principles methods. The band unfolding calculation results show that the donor level and acceptor level are, respectively, formed in the bandgap after the doping of W and Al. After the doping of Al, the formation energy of the oxygen vacancy decreases as the doping concentration increases. Instead, after the doping of W, the formation energy of the oxygen vacancy only undergoes an increase of 0.2 eV, and the diffusion barrier increases first and then decreases with the increase in the concentration of the doped W. After the doping of Al and W, the diffusion barriers of oxygen ions change within the ranges of 0.3–1.6 and 0.12–1.23 eV, respectively.