Dependence of Ferroelectric Properties on Thickness of BiFeO3 Thin Films Fabricated by Chemical Solution Deposition

Bismuth ferrite (BiFeO3) thin films were fabricated by depositing sol–gel solutions on Pt/Ti/SiO2/Si(100) structures. X-ray diffraction (XRD) showed that a polycrystalline phase and also a small fraction of a secondary phase, Bi2Fe4O9, were present in the film. The nonperovskite secondary phase decreased with increasing thickness, which showed the influence of volume effects on the film. Improved leakage current density and enhanced polarization in BiFeO3 films were observed. A 400-nm-thick film showed a leakage current on the order of 10-8 A/cm2 at room temperature. The remanent polarization was approximately 90 µC/cm2 at 80 K and the piezoelectric coefficient d 33 was approximately 50 pm/V.