Effects of Ho and Ti doping on structural and electrical properties of BiFeO3 thin films

Effects of Ho and Ti ions individual doping and co-doping on the structural, electrical, and ferroelectric properties of the BiFeO3 thin films are reported. Pure BiFeO3, (Bi0.9Ho0.1) FeO3, Bi(Fe0.98Ti0.02)O3+δ, and (Bi0.9Ho0.1)(Fe0.98Ti0.02)O3+δ thin films were prepared on Pt(111)/Ti/SiO2/Si(100) substrates by using a chemical solution deposition method. All thin films were crystallized in distorted rhombohedral structure containing no secondary or impurity phases confirmed by using an X-ray diffraction study. Changes in microstructural features, such as grain morphology and grain size distribution, for the doped samples were analyzed by a scanning electron microscopy. From the experimental results, a low electrical leakage (1.2 × 10 -5 A/cm2 at 100 kV) and improved ferroelectric properties, such as a large remnant polarization (2Pr) of 52 μC/cm2 and a low coercive field (2Ec) of 886 kV/cm, were observed for the (Bi0.9Ho0.1)(Fe0.98Ti0.02)O3+δ thin film. Fast current relaxation and stabilization observed in the (Bi0.9Ho0.1) (Fe0.98Ti0.02)O3+δ imply effective reduction and neutralization of charged free carriers.