The influence of La-substitution on the micro-structure and ferroelectric properties of chemical-solution-deposited BiFeO3 thin films

• Published in: Journal of physics. D, Applied physics Vol. 40; no. 9; pp. 2705 - 2709
• Main Authors: Singh, S K, Maruyama, K, Ishiwara, H
• Format: Journal Article
• Language: English
• Published: Bristol IOP Publishing 07.05.2007; Institute of Physics
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Dielectric properties of solids and liquids; Dielectrics, piezoelectrics, and ferroelectrics and their properties; Exact sciences and technology; Ferroelectricity and antiferroelectricity; Permittivity (dielectric function); Physics; Grain size; Polarization; Lanthanum oxides; Bismuth oxides; Leakage currents; Thin films; Ferroelectricity; Size effect; Iron oxides; Microstructure; Permittivity; Sol-gel process; Ferroelectric hysteresis
• ISSN: 0022-3727; 1361-6463
• DOI: 10.1088/0022-3727/40/9/004

La-substituted BiFeO3 (BFO) thin films were formed by depositing sol-gel solutions on Pt/Ti/SiO2/Si (1 0 0) structures. No secondary phase was observed by La-atom-substitution up to 20% in BFO thin films. The micro-structures of the films were changed with an increase in La concentration, which influenced the ferroelectric properties of the films. The dielectric constant of a BFO film was approximately 90 at 1 MHz and it increased to 125 in a 20% La-substituted BFO film, which was probably due to the size effect of grains. The substitution of La atoms in BFO films reduced the leakage current as well as remanent polarization. The leakage current contribution in the hysteresis loop was negligible when the loops were measured at above 20 kHz. The obtained saturated remanent polarization was 50 muC cm-2 in a 5% La-substituted BFO film at 100 kHz.