Properties of SrBi2Ta2O9 ferroelectric thin films prepared by a modified metalorganic solution deposition technique

Abstract

Polycrystalline ${\mathrm{SrBi}}_{\mathrm{2}}{\mathrm{Ta}}_{\mathrm{2}}{\mathrm{O}}_{\mathrm{9}}$ thin films having a layered-perovskite structure were fabricated by a modified metalorganic solution deposition technique using room temperature processed alkoxidecarboxylate precursor solution. It was possible to obtain a complete perovskite phase at an annealing temperature of 650 °C and no pyrochlore phase was observed even up to 600 °C. In addition, the ${\mathrm{SrBi}}_{\mathrm{2}}{\mathrm{Ta}}_{\mathrm{2}}{\mathrm{O}}_{\mathrm{9}}$ thin films annealed at 750 °C exhibited better structural, dielectric, and ferroelectric properties than those reported by previous techniques. The effects of postdeposition annealing on the structural, dielectric, and ferroelectric properties were analyzed. The electrical measurements were conducted on ${\mathrm{Pt/SrBi}}_{\mathrm{2}}{\mathrm{Ta}}_{\mathrm{2}}{\mathrm{O}}_{\mathrm{9}}\mathrm{/Pt}$ capacitors. The typical measured small signal dielectric constant and dissipation factor at 100 kHz were 330 and 0.023 and the remanent polarization and the coercive field were 8.6 ${\mathrm{\mu C/cm}}^{\mathrm{2}}$ and 23 kV/cm, respectively, for 0.25-μm-thick films annealed at 750 °C. The leakage current density was lower than ${10}^{\text{−8}}$ ${\mathrm{A/cm}}^{\mathrm{2}}$ at an applied electric field of 150 kV/cm. The films showed good switching endurance under bipolar stressing at least up to ${10}^{10}$ switching cycles.