Transition from nonvolatile bipolar memory switching to bidirectional threshold switching in layered MoO₃ nanobelts

Abstract

Resistive switching (RS) can be divided into two categories, namely nonvolatile memory switching and volatile threshold switching, depending on the volatility. MoO₃ is one type of versatile transition metal oxide with a high work function, large electron affinity and wide band gap for potential applications in electronics, optoelectronics, batteries and electrochromic devices. Herein, we report the transition from nonvolatile memory to volatile threshold switching in single MoO₃ nanobelts simply by changing the electrodes from Au to Ag. The one-dimensional (1D) α-MoO₃ nanobelts are synthesized by a hydrothermal method and annealed under different atmospheres to adjust the concentration of oxygen vacancies. The prepared single MoO₃ nanobelt is used to serve as the RS layer to construct lateral two-terminal RS devices. By using Au as the electrodes, the MoO₃ nanobelts exhibit typical nonvolatile bipolar memory RS behaviors. On the other hand, bidirectional threshold RS properties can be achieved by employing Ag as the electrodes due to the large contact resistance between Ag and MoO₃. More importantly, the threshold RS performance is significantly enhanced by annealing the nanobelts in N₂. The ON/OFF current ratio is increased up to 3 × 10⁵ while the threshold voltage is decreased down to 0.75 V. These results demonstrate the diverse RS behaviors in single 1D MoO₃ nanobelts and potential applications in volatile and non-volatile switching devices. In addition, the finding provides guidelines for improvement and/or alternation of RS behaviors through defect engineering and/or device modification in the multifunctional emerging devices.