Crystallographic and microstructural studies of BaTiO3 thin films grown on SrTiO3 by laser molecular beam epitaxy J. Vac. Sci. Technol. A 15, 275 (1997); 10.1116/1.580524 BaTiO3 thin films grown on SrTiO3 substrates by a molecular-beam-epitaxy method using oxygen radicals Epitaxial ultrathin films of BaTiO 3 were prepared using molecular beam epitaxy. For the substrate, ͑001͒-oriented SrTiO 3 single crystals were used. Controlling the growth conditions of these films as well as the semiconductor thin films, led to the successful growth of the BaTiO 3 films as single crystals, characterized by x-ray diffraction even in the ultrathin range. The ultrathin BaTiO 3 films are highly c-axis-oriented tetragonal phaselike bulk BaTiO 3 crystals. The tetragonality of the thin film crystals is much larger than bulk crystal's. We also measured the saturated polarization ( Ps͒ of the BaTiO 3 films at temperatures ranging from room temperature to 600°C. The results confirmed again that the films are ferroelectric tetragonal phase crystals. Moreover, they showed that the transition temperature for the ferroelectric-paraelectric phase transition of the films is higher than bulk crystal's.
Thin films of BaTiO3 have been epitaxially grown on Pt(001)/MgO(100) substrates by reactive evaporation. Structural and electrical properties were investigated as a function of film thickness. In situ reflection high-energy electron diffraction and cross-sectional transmission electron microscope observations have revealed that the BaTiO3 films are epitaxially grown on Pt/MgO substrates from the initial stage without any other phase formation. From the images of an atomic force microscope, it has been found that islands of BaTiO3 are present on the bare Pt surface at the initial stage of deposition; the island structure changes to a continuous layer above 1.2 nm in thickness and BaTiO3 grows in a two-dimensional mode. The lattice parameters and the dielectric properties are dependent on the film thickness. Thermodynamic theory was introduced to explain the thickness dependence of the relative dielectric constant εr. Good agreement between the experimental results and the theoretical calculations leads to the conclusion that the thickness dependencies of the lattice parameters and the dielectric constants are caused by the two-dimensional stress due to the lattice mismatch between Pt and BaTiO3 and/or the difference in the thermal expansion coefficients of BaTiO3 and the MgO substrate.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.