Excellent Selector Characteristics of Nanoscale VO₂ for High-Density Bipolar ReRAM Applications

We herein present a nanoscale vanadium oxide (VO₂) device with excellent selector characteristics such as a high on/off ratio (> 50), fast switching speed (20 ns), and high current density (>10^6\ A/cm^2). Owing to extrinsic defects, a large-area device with a 20-nm-thick VO₂ layer underwent an electrical short. In contrast, after scaling the device active area (, excellent switching uniformity was obtained. This can be explained by the reduced defects and the metal–insulator transition of the whole nanoscale VO₂. By integrating a bipolar resistive random access memory device with the VO₂ selection device, a significantly improved readout margin was obtained. The VO₂ selection device shows good potential for cross-point bipolar resistive memory applications.