Effect of post-deposition annealing pressure on bipolar resistive switching in RF sputtered BiFeO 3 /Nb:SrTiO 3 heterostructure

BiFeO 3 thin films were deposited on Nb-doped SrTiO 3 substrates by radio-frequency magnetron sputtering. They were annealed in 760 and 1.5 Torr of oxygen, respectively, and two resistive switching polarities were observed for the films. Their current density–voltage characteristics comply with space- charge-limited (SCL) conduction. For the BiFeO 3 thin film annealed at high oxygen pressure, the trapping/detrapping of charge carriers is responsible for its resistive switching effect. For the film annealed at low pressure, the density of oxygen vacancies is high, and the modulation of the interface Schottky barrier by the migration and accumulation of oxygen vacancies should play the dominant role in the resistive switching effect.