  BiFeO3 thin films are deposited on FTO coated glass substrates using a simple
sol-gel deposition technique, limiting thickness about 70 nm and Ag/BiFeO3/FTO
RRAM devices are prepared. The devices showed low-voltage bipolar switching
with the maximum Ion/Ioff ~ 450, and low set and reset voltages ~ 1.1 V and
-1.5 V, respectively. The devices are stable against on-off cycles with ~ 104 s
retention time without any significant degradation. The variations in the set
and reset voltages are 0.4 V and 0.6 V, respectively. We found that ohmic and
trap-controlled space charge limited conductions are responsible for low and
high resistance states, respectively. The resistive switching mechanism is
attributed to the formation and rupturing of the metal filament during the
oxidation and reduction of Ag ions for the set and reset states.
