Transient Current of Resistive Switching of a NiO_x Resistive Memory

A NiO_x thin film was fabricated by thermal oxidization on a Pt-coated substrate. Then, a Pt top electrode was deposited by an electron-beam evaporator to form a Pt/NiO_x/Pt structure. The NiO_x-based device can be reversibly switched between a high resistance-state (HRS) and a low resistance-state (LRS) by DC voltage sweeping. The resistive switching behavior occurs due to conducting filaments with a thermochemical reaction. A transient current was observed during the forming and SET processes (from a HRS to a LRS). The transient current increased with an increase in magnitude of the forming and SET voltage. The transient current was usually larger than the compliance current, and this caused the resistive switching behavior to be unstable. The transient current was caused by the discharge process of the parasitic capacitance of the measurement system. A circuit model of the measurement system was also proposed to simulate the transient current during the SET process. A resistor was series-wound with the NiO_x-based device to decrease the transient current during the forming and the SET processes. The series-wound resistor also increased the LRS resistance and reduced the RESET (from a LRS to a HRS) current.