Correlation between composition, microstructure, and ferroelectric properties of SrBi2Ta2O9 thin films

SrBi2Ta2O9 thin films prepared by a solution-deposition process were formed at various annealing temperatures. P-E hysteresis loops of the films exhibited well-defined shapes, and the leakage current decreased with increasing annealing temperature except for one annealed at 750 degrees C. The considerable amount of metallic Bi on the film surface diffused from the inner part was evaluated by a quantitative x-ray photoelectron spectroscopic analysis. A discontinuity in morphology such as cavities detected by transmission electron microscopic observation at grain boundaries between large single-crystal grains and microcrystallite regions, which was pronounced in the film annealed at 750 degrees C, is suggested as inducing an increase in leakage current by the condensation of metallic Bi at the cavities.