Theoretical studies on the switching mechanism of VMCO memories

In this work, we propose a new switching model for Vacancy Modulated Conductive Oxide (VMCO) memories which are non-filamentary resistive switching memories. In recent years, attention has been drawn to VMCO memories because the current through them depends on the area of the device. Since the switching mechanism in VMCO memories has not yet been clarified, we carried out first principles calculations to study this phenomenon. Previous studies have shown that a current path is created by the oxygen vacancies (Vo) in TiO2. We discovered that the formation and disappearance of Vo near the TiO2/a-Si interface in TiO2 can be controlled by applying a voltage, and that this could be used to control the current. From this, we proposed a new switching model for VMCO memories. [Display omitted] •Oxygen vacancies widely distributed in the oxide lead to a two-dimensional current in VMCO memories.•The formation and disappearance of oxygen vacancies near the TiO2/a-Si interface can be controlled by the applied voltage.•This model can explain the results of experimental measurements made on VMCO memories.