The microstructure and ferroelectric properties of Sm and Ta-doped bismuth titanate ferroelectric thin films

Sm–Ta co-doped Bi4Ti3O12 (Bi3.96Sm0.04Ti2.92Ta0.08O12, BSTTO) thin films were fabricated on Pt(111)/Ti/SiO2/Si(100) substrates by sol–gel technology, and the microstructure, dielectric, ferroelectric and leakage current properties of the thin films were investigated. BSTTO thin film exhibits a high remanent polarization (2Pr) of 46.2 μC/cm2 and a low coercive field (2Ec) of 102 kV/cm, fatigue-free characteristics up to ≧ 108 switching cycles. The 2Pr of the BSTTO thin film is larger than that of the Bi4Ti3O12 thin film (2Pr = 26 μC/cm2). In addition, the leakage current density of Sm–Ta co-doped Bi4Ti3O12 thin film is 2.56 × 10− 8 A/cm2, which is lower than that of the Bi4Ti3O12 thin film (1.0 × 10− 5 A/cm2). These improvements in the ferroelectric and leakage current properties can be attributed to the enhanced stability of the oxygen in the Ti–O octahedron layer by the substitution with Sm and Ta for Bi3 + and Ti4 + in A-site and B-site of the BTO thin film, respectively.

► Sm and Ta-doped Bi4Ti3O12 thin films were prepared by sol–gel technology.
► Films show preferred (117) orientation.
► The Sm and Ta-doping decrease the leakage current.
► The Sm and Ta-doping improved the ferroelectric and leakage current properties.