Interfacial Schottky-barrier-assisted optoelectronic resistive switching and synaptic plasticity in ITO/BiFeO3/ZnO/BiFeO3/Ag heterostructure memristors

An ITO/BiFeO3/ZnO/BiFeO3/Ag heterostructure memristor was fabricated by magnetron sputtering and post-annealing to investigate Schottky-barrier-assisted resistive switching and synaptic plasticity. Structural characterization confirms the formation of a compact BiFeO3/ZnO/BiFeO3 multilayer film with nanocrystalline morphology and distinct ZnO and BiFeO3 phases. The device exhibits stable bipolar resistive switching, and illumination enhances the resistance-state separation by modulating carrier concentration and oxygen-vacancy-related defect states. Transport analysis indicates Ohmic conduction at low bias, while Schottky emission dominates the higher-bias region, revealing the important role of BiFeO3/ZnO interfacial barriers. The switching behavior is primarily associated with oxygen-vacancy-assisted conductive pathway formation and rupture, while reversible Schottky barrier modulation at the heterointerfaces further regulates carrier transport. Furthermore, illumination- and pulse-interval-dependent long-term potentiation and depression are demonstrated, revealing optically tunable synaptic plasticity. These results suggest that the BiFeO3/ZnO/BiFeO3 heterostructure provides an effective platform for optoelectronic memristors and artificial synaptic devices.