Crystal structure and highly enhanced ferroelectric properties of (Tb, Cr) co-doped BiFeO3 thin films fabricated by a sol–gel method

BiFeO3 (BFO), Tb-doped BiFeO3 (BTFO) and Tb–Cr co-doped BiFeO3 (BTFCO) thin films were successfully prepared on SnO2: F (FTO)/glass substrates by a sol–gel method. The influence of Tb and Cr co-doping on the structure, leakage current, charge defects, dielectric and ferroelectric properties of the BTFCO thin film was investigated systematically. X-ray diffraction (XRD) and Raman spectroscopy results clearly reveal the structure transition and (110) preferentially oriented film texture for the co-doped thin film. BTFCO thin film becomes more compact structure and uniform than that of the other two films. The improved electrical properties of BTFCO thin film are observed in comparison with the BFO thin film. Furthermore, the highly enhanced ferroelectric property with a giant remanent polarization (2Pr=161.60 μC/cm2) and the decreased leakage current density (3.76×10−5 A/cm2 at 200 kV/cm) via co-doping Tb and Cr are obtained. The X-ray photoelectron spectroscopy (XPS) analyses clarify that the ratios of Fe2+/Fe3+ in the BFO and BTFCO thin films are calculated as 45:55 and 26:74, respectively, which indicate that the presence of Fe2+ ions is suppressed with co-doping Tb and Cr.