Ferroelectric properties of (001)- and (106)-oriented SrBi2Ta2O9 epitaxial thin films

Epitaxially grown SrBi2Ta2O9 (SBT) thin films with (001) and (106) orientations were prepared on La-doped SrTiO3 (001) and (110) substrates, respectively, by coating-pyrolysis process. When the films were annealed in air, their epitaxy was poor and no significant difference was observed in the P-E characteristics for the films that have different orientations. By contrast, the crystallinity and epitaxy of the films increased with decreasing oxygen partial pressure, p(O-2), of annealing atmosphere. Using these high quality epitaxial films, we observed a distinct difference in P-E hysteresis curves, which reflects the orientation of the films. After postannealing of these films in O-2 to compensate for possible oxygen deficiency, which might have been introduced into the SBT films owing to low p(O-2) annealing, the anisotropy of the ferroelectric response was maintained and almost the same P-E loops were obtained.