Hydrothermal Growth and Orientation of LaFeO₃ Epitaxial Films

LaFeO₃ thin films were successfully epitaxially grown on single-crystalline SrTiO₃ substrates by the one-step hydrothermal method at a temperature of 320 °C in a 10 mol/L KOH aqueous solution using La(NO₃)₃ and Fe(NO₃)₃ as the raw materials. The growth of the films was consistent with the island growth mode. Scanning electronic microscopy, elemental mapping, and atomic force microscopy demonstrate that the LaFeO₃ thin films cover the SrTiO₃ substrate thoroughly. The film subjected to hydrothermal treatment for 4 h exhibits a relatively smooth surface, with an average surface roughness of 10.1 nm. X-ray diffraction in conventional Bragg-Brentano mode shows that the LaFeO₃ thin films show the same out-of-plane orientation as that of the substrate (i.e., (001)_LaFeO3||(001)_SrTiO3). The in-plane orientation of the films was analyzed by φ-scanning, revealing that the orientational relationship is [001]_LaFeO3||[001]_SrTiO3. The ω-rocking curve indicates that the prepared LaFeO₃ films are of high quality with no significant mosaic defects.