Resistive switching behavior in epitaxial brownmillerite SrFeO_(2.5)/Nb:SrTiO_3 heterojunction

摘要

Epitaxial brownmillerite SrFeO_(2.5) thin films were deposited on conductive Nb-doped SrTiO_3 single crystal (001) and (111)-oriented substrates using pulsed laser deposition, and their resistive switching behavior was investigated. In both the (001) and (111) device configuration, the bottom SrFeO_(2.5)/Nb:SrTiO_3 interface exhibited Ohmic behavior, while the top Au/BM-SrFeO_(2.5) interface displayed Schottky-like contact. Unfortunately, no resistive switching behavior was observed in the (001) devices, where the oxygen vacancy channels of SrFeO_(2.5) are ordered along the in-plane direction of the device. Conversely, the (111)-grown SrFeO_(2.5) thin films with out-of-plane oriented ordered oxygen vacancy channels displayed excellent resistive switching behavior with a high on/off ratio (～10~4). The discrepancies between the (001) and (111) devices were explained in terms of their oxygen dynamics and corresponding topotactic phase transition in the SrFeO_(2.5) switching layer.