Coexistence of Bipolar and Unipolar Switching of Cu and Oxygen Vacancy Nanofilaments in Cu/TaOx/Pt Resistive Devices

Switching of a resistive Cu/TaOx/Pt device can be based on the formation of two types of nanofilament in the same device: Cu and oxygen vacancy conductive filaments, depending on the polarity of switching voltage. Cu/TaOx/Pt device can be switched in bipolar and unipolar regimes. The two types of conduction can be distinguished by different values of the resistance temperature coefficient. Both positive and negative voltages can reset the device when sufficient Joule heating is produced. The negative set voltages for oxygen vacancy filaments show higher absolute values than those for the Cu filaments. The unique fourfold switching property of a