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DF: Fachverband Dielektrische Festkörper

DF 11: Dielectric and ferroelectric thin films and nanostructures I

DF 11.8: Vortrag

Mittwoch, 27. Februar 2008, 16:20–16:40, EB 107

Probing ferroelectricity in ultrathin wedged epitaxial BaTiO₃ films — •Adrian Petraru¹, Hermann Kohlstedt¹, Axel Solbach², Nikolay Pertsev³, Uwe Klemradt², Willi Zander⁴, Jürgen Schubert⁴, and Rainer Waser¹ — ¹Institut für Festkoerperforschung und CNI, Forschungszentrum Jülich GmbH, Jülich, Germany — ²II. Physikalisches Institut B, RWTH Aachen University, 52074 Aachen, Germany — ³A. F. Ioffe Physico-Technical Institute, Russian Academy of Sciences, St. Petersburg, Russia — ⁴Institut für Bio - und Nanosysteme und CNI, Forschungszentrum Jülich GmbH, Jülich, Germany

High quality epitaxial wedged BaTiO₃ ultrathin films were grown epitaxially on SrRuO₃-covered (001) - oriented SrTiO₃ substrates by high-pressure sputtering. The composition along the wedge was checked by Rutherford Backscattering Spectrometry (RBS). The thickness slope and the in-plane and out-of plane lattice parameters of the wedge were studied by x-ray diffraction using a laboratory source and synchrotron radiation. The BaTiO₃ films were fully strained by the substrate. Ferroelectric capacitors were then fabricated from SrTiO₃/SrRuO₃/BaTiO₃(wedge)/SrRuO₃/Pt heterostructures using optical lithography and ion beam etching. Direct evidence of ferroelectricity in these films down to the thickness of 4 nm was obtained by measurements of polarization-voltage hysteresis loops.