Enhanced ferroelectric properties of Ce-substituted BiFeO3 thin films on LaNiO3/Si substrates prepared by sol-gel process

The effects of Ce substitution on the structural and electrical properties of multiferroic BiFeO3 thin films grown on LaNiO3/Si(100) substrates by a sol-gel process have been reported. X-ray diffraction data confirmed the substitutions of Ce into the Bi site with the elimination of all secondary phases under a substitution ratio x = 15%. The dielectric constants of the films increased from 90 to similar to 260 below 100 kHz with 5% molar Ce substitution and the films showed enhanced dielectric behavior. We observed a substantial increase in the remnant polarization (P-r) with Ce substitution and obtained a maximum value of similar to 71 mu C/cm(2) by 5% molar Cc incorporation. The leakage current behavior at room temperature of the films was studied and it was found that the leakage current density decreased from 10(-6) to 10(-8) A/cm(2) for 5% molar Ce-substituted films under a field 150 kV/cm. The reduction of dc leakage current of Ce-substituted films is explained on the basis of relative phase stability and improved microstructure of the material. (C) 2008 Elsevier Ltd. All rights reserved.