Electrode-induced polarity conversion in Nb2O5/NbOx resistive switching devices

Abstract

Applications in neuromorphic computing and next-generation memories require a deep understanding of the physical mechanisms in resistive switching (RS) devices. Here, we report electrode-induced polarity conversion in Nb2O5/NbOx RS devices, where Nb2O5 and NbOx are a switching layer and an oxygen vacancy (Vo··) reservoir, respectively. The reservoir provides the Vo·· s, comprising a conductive filament formed during an electroforming process. After the process, the devices with an inert Pt top electrode show a clockwise RS behavior. However, the ones with a reactive W top electrode exhibit a counterclockwise RS behavior. Detailed explorations suggest that reactive electrodes provide an oxygen ion reservoir near the active region of the conductive filaments. The reservoir dominates the rupture and recovery of the conductive filaments through interfacial redox reaction, which induces the switching polarity conversion. This study indicates that oxygen ion distribution and migration near a conductive filament tip have the dominant effect on switching processes of oxide RS devices.