Structural distortion and enhanced ferroelectric properties of Tb and Cr co-doped BiFeO3 thin films

BiFeO₃ and Bi_0.92Tb_0.08Fe_1?xCr_xO₃ (BTFCO) thin films were successfully prepared on SnO₂: F (FTO)/glass substrates by a chemical solution deposition technique. The influences of Tb and Cr co-doping on the structure, the leakage current, charge defects, the dielectric and the ferroelectric properties of the BTFCO thin films were investigated systematically. X-ray diffraction and Raman spectra results clearly reveal the structural distortion in the co-doped thin films. The X-ray photoelectron spectroscopy measurements show the absence of Fe²⁺ ions indicating the suppression of oxygen vacancies due to Tb and Cr co-doping. The electrical conduction mechanism of the BTFCO thin film is dominated by the Ohmic conduction in the low resistance state and trap-controlled space charged limited current in the high resistance state. With 8 %Tb and 1 %Cr co-doping, the film exhibits the superior ferroelectric (2P _r  = 105 μC/cm²) and dielectric properties. All the results show the film is very promising in the practical application.