Enhancement of ovonic threshold switching characteristics using nanometer-scale virtual electrode formed within ultrathin hafnium dioxide interlayer

Abstract

Herein, we investigate the effect of the active switching area on the electrical characteristics of an ovonic threshold switching (OTS) device. The active switching area was scaled-down below the conventional lithography limit by utilizing a nanometer-scale virtual electrode formed by the controlled breakdown of an ultrathin HfO2 interlayer. Improved switching characteristics were observed when the effective diameter of the virtual electrode was ∼6 nm. The bulk leakage current was blocked, which led to a reduction in the off-current by approximately two orders of magnitude. Furthermore, an improvement in the uniformity of the threshold voltage was observed. Our results showed that the optimal confinement of the active switching area is the key to achieve excellent performance, high reliability, and high tunability in an OTS device.