Abstract
Epitaxially grown bismuth layer-structured ferroelectric thin films have been prepared to provide a fundamental knowledge, such as the magnitude of the spontaneous polarization and domain dynamics. In the present study, a crystal structural modification utilizing their chemical anisotropy was attempted for epitaxially grown films to generate a noble function. a-/b-axis-oriented SrBi2Ta2O9, Bi4Ti3O12, and SrBi4Ti4O15 films were epitaxially grown on (101)TiO2 and (012)Al2O3 substrates by metalorganic chemical vapor deposition (MOCVD). Subsequently, these films were treated in diluted HCl. In the case of SBT films, only the Bi element was preferentially solved into the HCl, so that the (Bi2O2)2+-layer structure was changed. On the other hand, remarkable selectivity of constituent elements on the solubility was not observed for Bi4Ti3O12 and SrBi4Ti4O15 films. It was found that an artificial tetragonal phase keeping epitaxial growth was obtained for the epitaxial SrBi2Ta2O9 film after the HCl-treatment.
