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 (2P(r)) of 46.2 mu C/cm(2) and a low coercive field (2E(c)) of 102 kV/cm, fatigue-free characteristics up to >= 10(8) switching cycles. The 2P(r) of the BSTTO thin film is larger than that of the Bi4Ti3O12 thin film (2P(r)= 26 mu C/cm(2)). In addition, the leakage current density of Sm-Ta co-doped Bi4Ti3O12 thin film is 2.56x10(-8) A/cm(2), which is lower than that of the Bi4Ti3O12 thin film (1.0x10(-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 Bi3+ and Ti4+ in A-site and B-site of the BTO thin film, respectively. (C) 2012 Elsevier B.V. All rights reserved.