Berlin 2005 – scientific programme

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DF: Dielektrische Festkörper

DF 6: Dielektrische und ferroelektrische dünne Schichten und Nanostrukturen II

DF 6.2: Talk

Monday, March 7, 2005, 14:20–14:40, TU TC6

Impact of electrode interfaces on epitaxial Ba_0.7Sr_0.3TiO₃ thin film capacitors — •Regina Dittmann¹, Rafael Plonka², Nikolay Pertsev³, and Rainer Waser¹ — ¹Institut für Festk örperforschung and Center of Nanoelectronic Systems for Information Technology, Forschungszentrum Jülich, 52425 Jülich — ²Institut f ür Werkstoffe der Elektrotechnik, RWTH Aachen University of Technology, 52056 Aachen — ³A. F. Ioffe Physico-Technical Institute, Russian Academy of Sciences, 194021 St. Petersburg, Russia

We observed significant influence of the top-electrode material on the permittivity of Ba_0.7Sr_0.3TiO₃ (BST) thin-film capacitors epitaxially grown by pulsed laser deposition. For film thicknesses in the order of 100nm, SrRuO₃∖BST∖ SrRuO₃ thin-film capacitors exhibit a sharp paraelectric-to-ferroelectric phase transition at 350 K with a maximum permittivity of about 6660 [1]. This value is comparable to that of bulk ceramics and exceeds by several times the highest values reported for BST thin film capacitors. The phase transition temperature of SrRuO₃∖BST∖Pt samples with comparable thickness is 60 K lower and the maximum permittivity is about 3 times lower than those of samples with SrRuO₃ top electrode. For SrRuO₃∖ BST∖SrRuO₃ samples, the transition temperature shifts to lower temperatures with decreasing film thickness, whereas the samples with Pt top electrodes exhibit an opposite trend. Experimental results are analyzed theoretically in the light of the depolarizing-field and strain effects on the transition temperature and permittivity.

[1] R. Dittmann et al. Appl. Phys. Lett. 83, 5011 (2003)