Initial Growth Behavior of Ultra-Thin <i>c</i>-Axis-Oriented Epitaxial SrBi₂Ta₂O₉ films on SrTuO₃

<jats:title>Abstract</jats:title><jats:p><jats:italic>c</jats:italic>-axis-oriented epitaxial SrBi<jats:sub>2</jats:sub>Ta<jats:sub>2</jats:sub>O<jats:sub>9</jats:sub> ultra-thin films were grown by pulse-gas-introduced metalorganic chemical vapor deposition (pulsed-MOCVD) on (100)SrTiO<jats:sub>3</jats:sub> single crystal substrates with atomic scale step structure and their growth behavior was investigated by atomic force microscopy (AFM) and transmission electron microscopy (TEM). Minimum growth unit was found to be “ghalf-unit-cell” of SrBi<jats:sub>2</jats:sub>Ta<jats:sub>2</jats:sub>O<jats:sub>9</jats:sub>. Height of steps and width of terraces observed at SrBi<jats:sub>2</jats:sub>Ta<jats:sub>2</jats:sub>O<jats:sub>9</jats:sub> film surface were in good agreement with those at SrTiO<jats:sub>3</jats:sub> substrate surface. This shape transfer was induced by lattice displacement of SrBi<jats:sub>2</jats:sub>Ta<jats:sub>2</jats:sub>O<jats:sub>9</jats:sub> along c-direction formed at atomic step on SrTiO<jats:sub>3</jats:sub> substrate. In-plane growth of half-unit-cell SrBi<jats:sub>2</jats:sub>Ta<jats:sub>2</jats:sub>O<jats:sub>9</jats:sub> 2D-islands striding across the step walls was observed. It was considered to be a special phenomenon for c-axis-oriented films of layer-structured compounds due to their large crystal anisotropy and/or several times larger half-unit-cell height than single step one of SrTiO<jats:sub>3</jats:sub>.</jats:p>