Regensburg 2007 – scientific programme
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DS: Fachverband Dünne Schichten
DS 15: Poster Session
DS 15.47: Poster
Tuesday, March 27, 2007, 15:00–17:00, Poster B
Polarization coupled response of ZnO-BaTiO3 heterojunctions: A model approach — •Venkata Voora1, Tino Hofmann1, Matthias Brandt2, Mathias Schubert1, Michael Lorenz2, and Marius Grundmann2 — 1Department of Electrical Engineering , University of Nebraska-Lincoln, Lincoln, Nebraska, USA — 2Institut für Experimentelle Physik II, Universität Leipzig, Leipzig, Germany
Heterojunctions composed of wurtzite-structure ZnO and perovskite-structure BaTiO3 are very interesting because of the observed ionic lattice charge polarization coupling at their interface, which bears large potential for future device applications. Here we report on polarization hysteresis measurements on ZnO-BaTiO3 heterostructures with Pt front and back contacts deposited by pulsed laser deposition on (001) silicon substrate. The electrical data are analyzed using a physical model that accounts for the switchable spontaneous polarization of BaTiO3 and the non-switchable spontaneous polarization of ZnO. In this model we have implemented a polarization dependent net-interface-charge driven depletion layer, which represents the experimentally observed rectifying behavior of the heterostructure. We find a good agreement between our model generated data and our experiment, and we identify switching voltages and their conditions for the incompletely polarized ferroelectric ionic lattice polarization. We use our model to predict design of such heterostructures for switchable resistance and memory device structures. The influence of physical model parameters on the ZnO-BaTiO3 heterojunction characteristics will be discussed.