Interface and Defect Structures of (001)-Oriented SrBi2Ta2O9 Thin Film Epitaxially Grown on (001) SrTiO3 Single Crystal

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Abstract
Interface and defect structures of epitaxial c-axis oriented SrBi2Ta2O9 thin films on well lattice-matched (001) SrTiO3 substrates were crystallographically characterized by transmission electron microscopy. The film was coherently grown on the SrTiO3 substrate without interfacial layers and misfit dislocations, preserving the crystallographic relation of (001)[110] SrBi2Ta2O9//(001)[100] SrTiO3. The plausible atomic stacking sequence at the interface was found to be (SrTiO3 bulk)–SrO–TiO2–SrO–TaO2–Bi2O2–TaO2–SrO–(film bulk), where an electrically neutral SrO layer could be preferentially formed on the TiO2-terminated SrTiO3 substrate. High-resolution lattice images of the film showed that distinctive wedge-shaped contrasts could be attributed to the formation of c/6 translational boundaries originating from single unit cell steps on the SrTiO3 substrate.