Structural Characterization of BiFeO₃ Thin Films by Reciprocal Space Mapping

Abstract

High-resolution X-ray diffraction reciprocal space mapping (HRXRD-RSM) was applied for the structural characterization of epitaxial BiFeO3 thin film grown on SrRuO3-coated (001) SrTiO3 single crystal substrate with a variety of film thicknesses ranging from 15 to 500 nm. Distinguishing monoclinic structure from rhombohedral or tetragonal structures was accomplished with a set of HRXRD-RSMs measured for several hkl diffraction conditions. The BiFeO3 thin films showed both monoclinic and tetragonal structures depending on film thickness. Tetragonal structure was observed for film thicknesses below 50 nm and was highly strained due to epitaxial strain, while films with film thickness thicker than 50 nm showed monoclinic structure. No BiFeO3 thin films showed bulk rhombohedral structure. This structural change in BiFeO3 thin film may play an important role in the enhanced ferroelectricity observed.