$I$ – $V$ Characteristics of Antiparallel Resistive Switches Observed in a Single

A Cu/TaO_x/Pt resistive cell can transition from a high-resistance state to a low-resistance state by applying positive or negative set voltages. The set operation with positive bias is due to the electrochemical formation of a Cu conductive filament (CF), whereas the set operation with negative bias is attributed to the electroreduction of solid electrolyte and formation of an oxygen vacancy V_OCF. Both CFs can be reset by Joule heating. Since set voltages of the V_OCF have higher absolute values than those of the Cu CF, the switching based on Cu and V_O CFs can be decoupled within the same device. The device is inherently an antiparallel resistive switch circuit that can be consecutively switched between the Cu and V_OCFs.