Regensburg 2004 – scientific programme

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DF: Dielektrische Festkörper

DF 6: Nanostrukturen, Schichten und Keramiken

DF 6.7: Talk

Thursday, March 11, 2004, 12:10–12:30, H11

CURRENT TRANSPORT AND SIZE-EFFETCS IN ULTRA-THIN FERROELECTRIC BARRIERS — •H. Kohlstedt¹, N. A. Pertsev², J. Rodriguez-Contreras¹, A. Gerber¹, J. Schubert³, C. Jia¹, U. Poppe¹, and R. Waser¹ — ¹Forschungszentrum Jülich, Institut für Festkörperforschung and CNI, 52425 Jülich, Germany — ²A. F. Ioffe Physico-Technical Institute, 194021 St. Petersburg, Russia, — ³Forschungszentrum Jülich, Institut für Schichten- und Grenzflächen and CNI, 52425 Jülich, Germany

We will present our development of so-called ferroelectric tunnel junctions with the following layer sequence: SrTiO₃(substrate)/ SrRuO₃(electrode)/BaTiO₃ or PbZr_xTi_1−xO₃ (as ferroelectric)/SrRuO₃ or Pt as top electrode. These heterostructures have been investigated by XRD, RBS, AFM and HRTEM.

The aim of our work is to study fundamental aspects of electron tunnelling and electron transport through a ferroelectric material and the influence of the transport current on the ferroelectric polarization state of the barrier material. The I-V characteristics voltages showed switching events with two resistive states. The origin of the switching will be discussed in the framework of direct electron tunnelling, resonant tunneling, and electron transport via defects. For inelastic transport processes we found for temperatures below 100 K Glazman-Matveev tunneling and above 100 K a transition to Mott-hopping.

Moreover we will present a theoretical approach on the basis of the deformation potential model to combine the tunneling transfer matrix element with the strain state of the barrier.