Dresden 2006 – wissenschaftliches Programm

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DF: Dielektrische Festkörper

DF 3: Poster Session

DF 3.2: Poster

Montag, 27. März 2006, 09:30–17:00, P1

Thickness dependend dielectric properties of epitaxial Ba_0.7Sr_0.3TiO₃ thin film capacitors — •Regina Dittmann¹, Rafael Plonka², Nikolay Pertsev¹, and Rainer Waser^1,2 — ¹Institut für Festkörperforschung and Center of Nanoelectronic Systems for Information Technology, Forschungszentrum Jülich, 52425 Jülich — ²Institut für Werkstoffe der Elektrotechnik, RWTH Aachen University of Technology, 52056 Aachen

Single-crystalline all-perovskite SrRuO₃∖Ba_0.7Sr_0.3TiO₃ (BST) ∖ SrRuO₃ heterostructures have been grown epitaxially on SrTiO₃ by pulsed laser deposition. The samples exhibit a sharp paraelectric-to-ferroelectric phase transition with a maximum permittivity of about 6660. This value is comparable to that of bulk ceramics and exceeds by several times the highest values reported for BST thin film capacitors. At room temperature, the weak decrease of the permittivity with the BST thickness decreasing from 200 to 10 nm can be explained solely by the thickness-dependent strain relaxation in epitaxial films without assuming the presence of low-permittivity layers at the film/electrode interfaces. Furthermore, the ferroelectric-to-paraelectric phase transition temperature shifts to lower temperatures with decreasing film thickness. As a result, in the low temperature regime, where all samples are in the ferroelectric state, the permittivity increases with decreasing film thickness. This effect is analyzed with the aid of a thermodynamic theory and can be attributed to the influence of the depolarizing field originating from the incomplete screening of the SRO electrodes.