Ferroelectric properties of BiFexCr1-xO3 thin film formed on Pt electrodes

BiFe_xCr_1-xO₃ (x=0.4~0.6) thin films were formed on Pt/Ti/SiO₂/Si (100) substrates by chemical solution deposition. The spin-coated, dried and calcined films were finally annealed in a mixed gas of N₂ and O₂ (N₂:O₂=4:1) at 450, 500, 550 and 600°C. X-ray diffraction analysis revealed that polycrystalline grains of BiFeO₃ and BiCrO₃ coexist in the films, and that double perovskite Bi₂FeCrO₆ crystallites might also be included. The leakage current density measured at room temperature was lower than 1×10^-5 A/cm² in the films annealed at 450°C. The remanent polarization increased with increase of the Fe ratio, and a large value of 45 ¿C/cm² was obtained in the BiFe_0.6Cr_0.4O₃ thin film, when it was measured at 1.9 MV/cm and 50 kHz. Fatigue property was also improved and no degradation of the remanent polarization was observed in the BiFe_0.4Cr_0.6O₃ film by switching cycles up to 1 × 10⁸.