Tunable digital-to-analog switching in Nb2O5-based resistance switching devices by oxygen vacancy engineering

Abstract

Memristors have received tremendous attention recently for neuromorphic computing and high-density data storage due to their potential for miniaturization; however, the development and cost of microfabrication technologies required for device miniaturization have largely limited their neuromorphic computing applications. Herein, we investigate the transition from abrupt/digital to gradual/analog resistive switching (RS) behavior in Cu/Nb2O5/Pt memory devices. This transition is determined by the number of oxygen vacancies in the Nb2O5 switching layer by regulating the deposition temperature from 250 °C to 400 °C, which was prepared by pulsed laser deposition on a Pt (150 nm)/Ti/SiO2/Si substrate. The XPS results revealed that the oxygen vacancy concentration in the Nb2O5 switching layer increased gradually upon increasing the deposition temperature. By increasing the oxygen vacancy concentration in the switching layer, the reset process changed from abrupt to gradual switching, and the set process changed from abrupt to stepwise switching for the Cu/Nb2O5/Pt memory devices. In addition, the dynamically controllable oxygen vacancy concentration related to the formation/rupture of oxygen vacancy conducting filaments is suggested to be responsible for the RS behavior in Cu/Nb2O5/Pt memory devices. This work provides a new opportunity to tailor the RS behavior in memory devices by oxygen engineering and paves the way for research into analog artificial synapses.