Dresden 2009 – wissenschaftliches Programm

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DF: Fachverband Dielektrische Festkörper

DF 6: Poster I

DF 6.10: Poster

Dienstag, 24. März 2009, 09:30–12:30, P5

Strain and electric field effects on the dielectric permittivity of epitaxial SrTiO₃ thin films — •Sebastian Engmann, Veit Grosse, Robert Haehle, Janine Fischer, and Paul Seidel — Institut für Festkörperphysik, Friedrich-Schiller-Universität Jena, Helmholtzweg 5, 07743 Jena

We present measurements of the dielectric permittivity of epitaxial SrTiO₃ (STO) thin films. Therefore we prepared capacitor structures based on the multilayer system YBa₂Cu₃O_7−x/STO/Au grown by pulsed laser deposition on LaAlO₃ substrates. Rocking curves prove good c-axis orientation of the STO crystallites. Due to epitaxial strain for thin films the c-axis is enlarged up to values of 3.932 Å and relaxes to bulk values for a film thickness of 170 nm. From capacitance measurements in the temperature range from 293 to 4.2 K we determined the dielectric permittivity for different film thicknesses. An external electric bias field was varied to compensate for internal fields caused by band alignment due to the difference in work function of both electrodes. We discuss the results as a series connection of the film and interface capacitances involving strain effects.