Ferroelectric Properties of MBi4Ti4O15 (M = Sr, Pb, Ca) Thin Films

Abstract

Among the ferroelectric bismuth layered perovskites belonging to Aurivillius family, the MBi4Ti4O15 (MBT15, M = Sr, Ca, Pb) thin films have been fabricated by a chemical solution deposition technique, and their structures and ferroelectric properties were investigated in this work. The SrBi4Ti4O15 (SBT15) film fabricated on IrO2 presented the highest remanent polarization (Pr) among the films in this series. It demonstrated a saturated hysteresis loop at 5 V with Pr of 19 μ C/cm2 and coercive field (Ps) of 116 kV/cm. The PbBi4Ti4O15 (PBT15) thin films were selectively controlled in c-axis and off-c-axis orientation on Pt layer by adjusting the annealing condition. The off-c-axis oriented PbBi4Ti4O15 film demonstrated considerably higher Pr (8.7 μ C/cm2) than that of c-axis oriented film (3.7 μ C/cm2). Regardless of grain orientation, however, PBT15 films were not fatigued up to 1010 cycles under 9V application. The CaBi4Ti4O15 (CBT15) thin films were also produced on Pt and IrO2 electrode, respectively, by controlling the annealing condition. The CBT15 film on IrO2 presented higher Pr (∼10.8 μ C/cm2) than that of film (∼ 6.7 μ C/cm2) on Pt. † Present address: Samsung Advanced Institute of Technology, P.O. Box 111, Suwon 440-600, Korea