Resistive-switching crossbar memory based on Ni-NiO core-shell nanowires

摘要

Resistive-switching memory (RRAM) is an emerging nanoscale device based on the localized metal-insulator transition within a few-nanometer-sized metal oxide region. RRAM is one of the most promising memory technologies for the ultimate downscaling of nonvolatile memory. However, to develop memory arrays with densities approaching 1 Tb cm-2, bottom-up schemes based on synthesis and assembly of metal oxide nanowires (NWs) must be demonstrated. A RRAM memory device based on core-shell Ni-NiO NWs is presented, in which the Ni core plays the role of the metallic interconnect, while the NiO shell serves as the active switching layer. A resistance change of at least two orders of magnitude is shown on electrical operation of the device, and the metal-insulator switching is unequivocally demonstrated to take place in the NiO shell at the crossing between two NWs or between a NW and a gold electrode strip. Since the fabrication of the NW crossbar device is not limited by lithography, this approach may provide a basis for high-density, low-cost crossbar memory with long-term storage stability. Self-assembled crossbar junctions featuring resistive switching are developed from core-shell nanowires. Ni nanowires (NWs) are first grown by electroplating in a template. The nanowires are then thermally oxidized to obtain the core-shell Ni-NiO structure, and crossbar junctions are developed by magnetic alignment and electron-beam lithography of the electrical contacts. Nonvolatile resistance switching with a resistance window of more than five decades is shown, which is evidence for metal-insulator transition at the cross-point junction between the two core-shell NWs.