Interface polarization coupling in piezoelectric-semiconductor ferroelectric heterostructures

Authors

Venkata M. Voora, University of Nebraska-Lincoln
Tino Hofmann, University of Nebraska-LincolnFollow
M. Brandt, Institut für Experimentelle Physik II, Universität Leipzig, 04103 Leipzig, Germany
M. Lorenz, Institut für Experimentelle Physik II, Universität Leipzig, 04103 Leipzig, Germany
M. Grundmann, Institut für Experimentelle Physik II, Universität Leipzig, 04103 Leipzig, Germany
N. Ashkenov, Institut für Experimentelle Physik II, Universität Leipzig, 04103 Leipzig, Germany
H. Schmidt, Institut für Ionenstrahlphysik und Materialforschung, Forschungszentrum Dresden-Rossendorf e.V., 01328 Dresden, Germany
Natale J. Ianno, University of Nebraska-LincolnFollow
Mathias Schubert, University of Nebraska-LincolnFollow

Date of this Version

2010

Comments

Published in PHYSICAL REVIEW B 81, 195307 (2010). Copyright ©2010 The American Physical Society. Used by permission.

Abstract

We present a dielectric continuum model approach for studying the electrical polarization properties of interface polarization coupled BaTiO₃, BaTiO₃-ZnO, and ZnO-BaTiO₃-ZnO thin-film structures consisting of several hundred nanometer thick layers. Our model augments the effects of electric field driven switchable polarization and depletion layer formation with spontaneous interface polarization coupling. Wurtzite-structure (piezoelectric) n-type ZnO and perovskite-structure (ferroelectric) highly insulating BaTiO₃ layers were prepared and investigated. The coupling between the nonswitchable spontaneous polarization of ZnO and the electrically switchable spontaneous polarization of BaTiO₃ causes strong asymmetric polarization hysteresis behavior. The n-type ZnO reveals hysteresis-dependent capacitance variations upon formation of depletion layers at the ZnO/BTO interfaces. We obtain a very good agreement between our model generated data and our experiment. Our model approach allows for derivation of the amount and orientation of the spontaneous polarization of the piezoelectric constituents and can be generalized toward multiple-layer piezoelectric-semiconductor ferroelectric heterostructures. We identify interface polarization coupled triple-layer ZnO-BTOZnO heterostructures as two-terminal unipolar ferroelectric Bi-junction transistor for use in memory storage.