Initial states and analog switching behaviors of two major tantalum oxide resistive memories

A systematic study was performed to understand the two major operation modes, valence change memory (VCM) and electrochemical memory (ECM), of tantalum oxide resistive memory, which were categorized by the type of conductive filament. The tantalum oxide insulator layer was predictably fabricated to modify the pristine oxygen-vacancy concentration in the insulator layer, where tantalum and copper top electrodes were used to achieve VCM and ECM modes. The distinguishable characteristics of the initial state and analog resistive switching operation revealed the prerequisites for switching capabilities and demonstrated the effects of oxygen vacancies in the two switching modes.