Ca doping dependence of resistive switching characteristics in ferroelectric capacitors comprising Ca-doped BiFeO_3

摘要

We have investigated the transport and ferroelectric properties of ferroelectric capacitors comprising Ca-doped BiFeO_3 (BFO) to elucidate the correlation between resistive switching and ferroelectricity. A capacitor consisting of Ca-doped (3.6 at. %) BFO film exhibited polarization-voltage hysteresis, indicating ferroelectricity of the film. As the Ca-doping ratio was increased, the leakage current increased, and zero-crossing hysteretic current-voltage characteristics, i.e., bipolar resistive switching, were observed in capacitors consisting of Ca-doped BFO films with doping ratios of 6.4-13 at. %. A capacitor consisting of a highly Ca-doped BFO (23 at. %) film showed neither resistive switching nor ferroelectric behavior. Distinct changes in the retention and pulsed-voltage-induced resistive switching characteristics were observed around a Ca-doping ratio of 9.0 at. %. The Ca-doping dependence of the resistive switching appeared to correlate with the ferroelectric phase diagram of the Ca-doped BFO films [Yang et al, Nat. Mater. 8, 485 (2009)].