Top electrode dependence of the write-once-read-many-times resistance switching in BiFeO₃ films

The electrode is one of the key factors that influences and controls the resistive switching characteristic of a resistive switching device. In this work, we investigated the write-once-read-many-times (WORM)-resistive switching behavior of BiFeO₃ (BFO)-based devices with different top electrodes, including Pt, Ag, Cu, and Al. The WORM-resistive switching behavior has been observed in Pt/BFO/LaNiO₃ (LNO), Ag/BFO/LNO, and Cu/BFO/LNO devices. In the initial high resistance state, the Pt/BFO/LNO device shows space-charge-limited current conduction due to the large Schottky barrier height at the Pt/BFO interface, while the Ag/BFO/LNO and Cu/BFO/LNO devices exhibit Schottky emission conduction due to the small barrier height at both top electrode/BFO and BFO/LNO interfaces. In the low resistance state, the metallic conduction of the Pt/BFO/LNO device is a result of the formation of conduction filaments composed of oxygen vacancies, and yet the metallic conduction of Ag/BFO/LNO and Cu/BFO/LNO devices is due to the formation of oxygen vacancies-incorporated metal conduction filaments (Ag and Cu, respectively). The observed hysteresis I-V curve of the Al/BFO/LNO device may be attributed to oxygen vacancies and defects caused by the formation of Al–O bond near the Al/BFO interface. Our results indicate that controlling an electrode is a prominent and feasible way to modulate the performance of resistive switching devices.