In situ observation of nickel as an oxidizable electrode material for the solid-electrolyte-based resistive random access memory

In this letter, we dynamically investigate the resistive switching characteristics and physical mechanism of the Ni/ZrO₂/Pt device. The device shows stable bipolar resistive switching behaviors after forming process, which is similar to the Ag/ZrO₂/Pt and Cu/ZrO₂/Pt devices. Using in situ transmission electron microscopy, we observe in real time that several conductive filaments are formed across the ZrO₂ layer between Ni and Pt electrodes after forming. Energy-dispersive X-ray spectroscopy results confirm that Ni is the main composition of the conductive filaments. The ON-state resistance increases with increasing temperature, exhibiting the feature of metallic conduction. In addition, the calculated resistance temperature coefficient is equal to that of the 10-30 nm diameter Ni nanowire, further indicating that the nanoscale Ni conductive bridge is the physical origin of the observed conductive filaments. The resistive switching characteristics and the conductive filament's component of Ni/ZrO₂/Pt device are consistent with the characteristics of the typical solid-electrolyte-based resistive random access memory. Therefore, aside from Cu and Ag, Ni can also be used as an oxidizable electrode material for resistive random access memory applications.