In this paper, BiFeO3 (BFO), Bi0.95Sm0.05FeO3 (BSF), BiFe0.95Ti0.05O3 (BFT) and Bi0.95Sm0.05Fe0.95Ti0.05O3 (BSFT) thin films were deposited on the Pt (111)/TiO2/SiO2/Si(100) substrates by sol-gel technique. X-ray diffraction and scanning electron microscope measurements explain that increased lattice constant and uniform surface morphology can be obtained by Sm-Ti co-substitution in BFO thin film. Meanwhile, the dielectric constant is improved up to 230 at 100 kHz and the leakage current density decreases to 1.5 x 10(-5) A/cm(2) at 300 kV/cm. Consequently, the ferroelectricity of BSFT thin film is remarkably enhanced with 2Pr of 17.024 mu C/cm(2) at 563 kV/cm. The electrical conductivity of BSFT film at 387 kV/cm is calculated to be 2.8 x 10(-12) Omega(-1) cm(-1). (C) 2011 Elsevier B.V. All rights reserved.