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DF: Fachverband Dielektrische Festkörper
DF 7: Dielectric and Ferroelectric Thin Films and Nanostructures I
DF 7.6: Talk
Tuesday, March 27, 2007, 16:30–16:50, H11
Resistive Switching in Ferroelectric Materials — •Hermann Kohlstedt1, Adrian Petraru1, Kristoff Szot1, Valanoor Nagarajan2, Ulrich Poppe1, Wolgang Speier1, and Rainer Waser1 — 1Institut für Festkörperforschung (IFF) and CNI, Forschungszentrum Jülich GmbH, Jülich, Germany — 2School of Materials Science and Engineering, UNSW, NSW 2052, Sydney
We investigated the resistive switching effect in SrRuO3/PbZr0.2Ti0.8O3/Pt ferroelectric capacitors. By using a conductive atomic force microscope the piezoelectric response, the capacitance as well as the resistive current vs. the applied bias voltage was simultaneously measured. The piezoelectric response and the capacitance butterfly loop showed clear indication that the PZT films were ferroelectric. We determined a coercive field of 167 kV/cm in 30 nm thick PZT films. By increasing the bias electric field approximately a factor two larger then the coercive field we observed an electric forming process, i.e. the resistance changed strongly. Hereafter the devices showed bipolar resistive switching. The simultaneously recorded piezoelectric response data showed that after the electric forming procedure the film was ferroelectric. The difference between the coercive field and the resistive switching voltage is explained on the basis of a filament model in which the resistive switching and ferroelectricity are considered as independent phenomena. This model is supported by measurements of the resistance times area (R x A) product. Parasitic effects during the measurements of the piezo response during I-V curve cycling will be discussed.