Effect of La substitution on structural and electrical properties of BiFeO3 thin film

Abstract

The effect of La substitution on the structural and electrical properties of multiferroic $\mathrm{Bi}\mathrm{Fe}{\mathrm{O}}_3$ thin films grown on $\mathrm{Pt}∕\mathrm{Ti}{\mathrm{O}}_2∕\mathrm{Si}{\mathrm{O}}_2∕\mathrm{Si}$ substrates by pulsed laser deposition has been reported. X-ray diffraction data confirmed the substitutions of La into the Bi site with the elimination of all of the secondary phases. The dielectric constant of the films was systematically increased from 165 to $\sim 350$ and the films showed excellent dielectric loss behavior. We observed a gradual increase in the remnant polarization $\left(2P_r\right)$ with lanthanum substitution obtaining a maximum value of $\sim 42\mu \mathrm{C}∕{\mathrm{cm}}^2$ at $20\mathrm{mol}\%$ La incorporation. The leakage current behavior at room temperature of the films was studied and it was found that the leakage current decreased from ${10}^{-4}\text{to}{10}^{-7}\mathrm{A}∕{\mathrm{cm}}^2$ for La-substituted films at a field strength of $50\mathrm{kV}∕\mathrm{cm}$ . The reduction of dc leakage current of La-substituted films is explained on the basis of relative phase stability and improved microstructure of the material.