Microstructure and properties of epitaxial ferroelectric bismuth-layered perovskite thin films grown in Si(100) with a polarization component perpendicular to the film plane

Epitaxial ferroelectric films of the bismuth-layered perovskites SrBi₂Ta₂O₉ and Ba₂Bi₄Ti₅O₁₈ with uniform (116)- and (001)-orientation, resp., are grown by laser deposition on Si(100) substrates covered with suitable epitaxial buffer and electrode layers. These films have a component of the spontaneous polarization perpendicular to the film plane, as it is required in NV-FRAM applications. Crystallographic orientations are analysed by XRD, ferroelectrical properties including fatigue behaviour are determined, and microstructure investigations are performed by AFM and (high-resolution) TEM of plan-view and cross section samples. Specific, non-trivial in-plane orientations, multiple twins, and new types of lattice defects have been observed and are discussed.