Perfection of leakage and ferroelectric properties of Ni-doped BiFeO3 thin films

BiFe1-xNixO3 (x = 0%, 1, 2 and 3%) films were deposited on ITO/glass substrate using sol-gel process. The work reports the impacts of Ni doped on the crystal microstructure, leakage current, conduction mechanism and ferroelectric behaviour systematically. From the XRD analysis, all samples match well with the perovskite structure without impurity phase. Polarisation-electric filed hysteresis loop demonstrates that the optimal Ni-doped content of BiFeO3 films is x = 2%, of which the remnant double polarisation (2P(r)) is 141.4 C/cm(2) at the test electric field of 1067 kV/cm. Leakage current density curves show that Ni doping has a great contribution in reducing leakage. The value of leakage is 4.79 x 10(-7) A/cm(2) at tested electric field of 300 kV/cm. In addition, the leakage conduction mechanism transforms from the Ohmic conduction under the low electric field into the space charge limited conduction under high electric field. Ni doped does not cause significant change in the conduction mechanism.