Enhanced electrical insulation and ferroelectricity in La and Ni co-doped BiFeO3 thin films

In this manuscript, we report the effect of co-doping of La and Ni in controlling the electrical leakage and enhancing the ferroelectric polarization in chemical solution processed BiFeO3 (BFO) thin films grown on Pt/Si substrates. Structural analysis of the films using X-ray diffraction shows that all the films are phase pure with perovskite structure and a R3c space group. The films are polycrystalline without evidence of any preferred orientation. Compared to the undoped BFO thin films, the leakage current in co-doped thin films is minimum at a La doping of 5 at% and Ni doping of 2.5 at% beyond which the leakage increases. While ferroelectric polarization does decrease marginally on co-doping, the shape of ferroelectric hysteresis loop improves in comparison to the undoped or singly doped films. The samples with La doping of 5 at% and Ni doping of 2.5 at% (Bi0.95La0.05Fe0.975Ni0.025O3) show a remnant polarization (Pr) of ∼66 μC/cm2 and a coercive field of 0.3 MV/cm at room temperature.