  BiFeO3 thin films have been deposited on Pt/sapphire and Pt/Ti/SiO2/Si
substrates with pulsed laser deposition using the same growth conditions,
respectively. Au was sputtered as the top electrode. The microscopic structure
of the thin film varies by changing the underlying substrate. Thin films on
Pt/sapphire are not resistively switchable due to the formation of Schottky
contacts at both the top and the bottom interface. However, thin films on
Pt/Ti/SiO2/Si exhibit an obvious resistive switching behavior under forward
bias. The conduction mechanisms in BiFeO3 thin films on Pt/sapphire and
Pt/Ti/SiO2/Si substrates are discussed to understand the different resistive
switching behaviors.
