$I$– $V$ Characteristics of Antiparallel Resistive Switches Observed in a Single $\hbox{Cu/TaO}_{x}\hbox{/Pt}$ Cell

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
_O
CF. Both CFs can be reset by Joule heating. Since set voltages of the
V
_O
CF 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
_O
CFs.