OXIDE FERROELECTRIC MATERIALS GROWN BY METALORGANIC CHEMICAL VAPOR-DEPOSITION

Various ferroelectric perovskite-type oxides have been successfully grown by using the metalorganic chemical vapor deposition technique. In particular, the results obtained for the growth of PbTiO3, BaTiO3, and PZT are reported. PbTiO3 thin films grown on fused quartz and Si(100) were polycrystalline and were fully textured with the a- and c-axes perpendicular to the surface. Epitaxy was achieved on the (001) surfaces of the single crystals KTaO3, SrTiO3, and MgO. The MOCVD process and thin-film properties are discussed along with our recent work on the prediction of thin-film properties by using a Landau-Ginzburg-Devonshire type free-energy functional. The ferroelectric properties and domain orientation of epitaxial PbTiO3 thin films strongly depend on the substrate used and on film thickness in the range of 200-8000 angstrom. The spontaneous polarization decreased with decreasing thickness for films grown on KTaO3. The films grown on KTaO3 consist of periodic alternating a- and c-domains with 90-degrees domain walls making an angle of about 45-degrees with the surface.