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

Sm–Ta co-doped Bi 4 Ti 3 O 12 (Bi 3.96 Sm 0.04 Ti 2.92 Ta 0.08 O 12 , BSTTO) thin films were fabricated on Pt(111)/Ti/SiO 2 /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 (2 P r ) of 46.2 μC/cm 2 and a low coercive field (2 E c ) of 102 kV/cm, fatigue-free characteristics up to ≧ 10 8 switching cycles. The 2 P r of the BSTTO thin film is larger than that of the Bi 4 Ti 3 O 12 thin film (2 P r = 26 μC/cm 2 ). In addition, the leakage current density of Sm–Ta co-doped Bi 4 Ti 3 O 12 thin film is 2.56 × 10 − 8 A/cm 2 , which is lower than that of the Bi 4 Ti 3 O 12 thin film (1.0 × 10 − 5 A/cm 2 ). 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 Bi 3 + and Ti 4 + in A-site and B-site of the BTO thin film, respectively.