Regensburg 2010 – scientific programme
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KR: Fachverband Kristallographie
KR 1: Tutorial: Functional (oxide) single crystals and epitaxial films - from growth to function
KR 1.3: Tutorial
Sunday, March 21, 2010, 17:30–18:15, H4
Epitaxial ferroelectric oxide thin films, nanostructures, and superlattices — •Dietrich Hesse, Ionela Vrejoiu, and Marin Alexe — Max Planck Institute of Microstructure Physics, Halle, Germany
Epitaxial ferroelectric thin films, nanostructures and superlattices represent a particularly interesting part of functional materials. In this tutorial, fundamental terms of epitaxial growth will be presented, along with a detailed characterization of growth-structure-property relations of a number of examples of perovskite-type ferroelectric structures. E.g., it will be shown how remanent polarization and switchability of pulsed-laser deposited Pb(Zr,Ti)O3 (PZT) epitaxial thin films depend on the defect content (threading dislocations, stacking faults), and how the properties of antiferroelectric/ferroelectric PbZrO3/PZT superlattices depend on the thickness of the individual layers via strain. The properties of epitaxial, ferroelectric (Bi,La)4Ti3O12 nanostructures and Pt/PZT/Pt nanocapacitors of sub-100 nm size are shown to be determined by crystallographic orientation, crystal perfection, and size. The role of 2D defects will be highlighted, viz. ferroelectric 90 degree domain boundaries in epitaxial PZT films serving as nucleation centers for 180 degree switching, and the atomic structure of 180 degree boundaries influencing the switching process. Overall the interesting physical properties of epitaxial functional perovskite structures are discussed in terms of growth, crystal orientation, defect type, defect content, and strain.