Revealing Resistive Switching Mechanism in CaFeO_x Perovskite System with Electroforming‐Free and Reset Voltage‐Controlled Multilevel Resistance Characteristics

Abstract

Recently, perovskite (PV) oxides with ABO₃ structures have attracted considerable interest from scientists owing to their functionality. In this study, CaFeO_x is introduced to reveal the resistive switching properties and mechanism of oxygen vacancy transition in PV and brownmillerite (BM) structures. BM-CaFeO_2.5 is grown on an Nb-STO conductive substrate epitaxially. CaFeO_x exhibits excellent endurance and reliability. In addition, the CaFeO_x also demonstrates an electroforming-free characteristic and multilevel resistance properties. To construct the switching mechanism, high-resolution transmission electron microscopy is used to observe the topotactic phase change in CaFeO_x . In addition, scanning TEM and electron energy loss spectroscopy show the structural evolution and valence state variation of CaFeO_x after the switching behavior. This study not only reveals the switching mechanism of CaFeO_x , but also provides a PV oxide option for the dielectric material in resistive random-access memory (RRAM) devices.