Improved oxygen ion migration efficiency and resistive switching properties in SrFeOx memristor with vertical superlattice-like structure

Abstract

The resistive switching (RS) behaviour between high and low resistance states in SrFeOx memristors originates from topological phase transition (TPT) induced by the migration of oxygen ions. Accelerating the migration of oxygen ions in the anisotropic crystal structure of SrFeO2.5 is of great importance for improving the RS properties and promoting the application for this TPT memristor. In this study, SrFeOx TPT memristors with different superlattice-like (SLL) structures were fabricated and the prepared devices with a vertical-type SIL structure display an ultra-low operation voltage of only 0.6 V, excellent cycling stability, data retention, and endurance performance. Moreover, the microstructures of vertical and horizontal SLL SrFeO2.5 were characterized with X-ray diffraction and transmission electron microscope. Furthermore, the differences in oxygen ion migration rate in the two structures were also tested by in-situ X-ray photoelectron spectroscopy. Finally, the optical band gaps and oxygen ion migration barriers of the two structures were calculated using first principles. All the characterizations and simulation results prove that the vertical type SrFeOx shows a higher oxygen ion migration efficiency. More encouragingly, the vertical SLL devices exhibit up to 96 % recognition accuracy for the Mixed National Institute of Standards and Technology image recognition task.