Structural transitions and enhanced ferroelectricity in Ca and Mn co-doped BiFeO3 thin films

Ca and Mn co-doped BiFeO3 (BFO) thin films were fabricated on (111) Pt/Ti/SiO2/Si substrates via a simple solution approach. Enhanced ferroelectric properties were obtained in these Ca and Mn co-doped BFO films, e. g., large remnant polarization value (P-r similar to 89 mu C/cm(2)) and large remnant polarization to saturated polarization ratio (P-r/P-s similar to 0.84) for Bi0.90Ca0.10Fe0.90Mn0.10O3 film. X-ray diffraction and Raman spectra of these films showed that B-site Mn doping causes substantial structural transition toward orthorhombic phase and A-site Ca doping facilitates an evolution to tetragonal phase with higher crystal symmetry. The structural transitions are in favor of enhanced ferroelectric properties in the BFO films. The approach of A and B site co-doping is proved to be effective in enhancing ferroelectric performance in multiferroic BFO films. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3650460]