Dresden 2009 – scientific programme

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DF: Fachverband Dielektrische Festkörper

DF 12: Poster II

DF 12.1: Poster

Wednesday, March 25, 2009, 09:30–12:30, P5

Cr doping of epitaxial PbZr_0.2Ti_0.8O₃ films — •Ludwig Feigl¹, Eckhard Pippel¹, Ionela Vrejoiu¹, Rüdiger-A. Eichel², Emre Erdem², Roland Mattheis³, Marin Alexe¹, and Dietrich Hesse¹ — ¹Max Planck Institute of Microstructure Physics, Weinberg 2, D-06120 Halle, Germany — ²Institut für Physikalische Chemie I, Universität Freiburg, D-79104 Freiburg, Germany — ³Institut für Photonische Technologien (IPHT), D-07702 Jena, Germany

RBS investigations suggested that Cr impurities are present in epitaxial PZT20/80 films deposited from a stoichiometric Pb_1.1Zr_0.2Ti_0.8O₃ target by PLD. To investigate the possible impact of these impurities on the properties of the films, Cr doped PZT20/80 films were deposited onto a SrRuO₃ electrode grown on a vicinal (100) SrTiO₃ substrate. Various dopant concentrations can be achieved by alternately ablating a pure and a highly doped PZT20/80 target. The structural properties are investigated by means of TEM both in conventional and in high resolution scanning mode combined with EDX. Measurements of the polarization, the dielectric constant and the leakage current in dependence on the applied voltage were performed. The Schottky model is used to derive the electronic properties of the film. The Cr is found to (I) increase the leakage current through a reduction of the Schottky barrier; (II) change the film growth by facilitating relaxation. As shown by EPR, Cr is incorporated at the octahedrally coordinated [Zr,Ti]-site, acting as an acceptor and favoring a directly coordinated oxygen vacancy to the chromium center for partial charge compensation. The dipole is oriented parallel to the spontaneous polarization.