Abstractc-axis-oriented epitaxial SrBi2Ta2O9 ultra-thin films were grown by pulse-gas-introduced metalorganic chemical vapor deposition (pulsed-MOCVD) on (100)SrTiO3 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 SrBi2Ta2O9. Height of steps and width of terraces observed at SrBi2Ta2O9 film surface were in good agreement with those at SrTiO3 substrate surface. This shape transfer was induced by lattice displacement of SrBi2Ta2O9 along c-direction formed at atomic step on SrTiO3 substrate. In-plane growth of half-unit-cell SrBi2Ta2O9 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 SrTiO3.
Initial growth behavior of bismuth on Ag(111) and Au(111)
