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Self-selective Epitaxial Growth of BST Films: toward Nano-composite Structure for Microwave Tunable Devices

Published online by Cambridge University Press:  01 February 2011

Tomoaki Yamada ,
Vladimir O. Sherman ,
Andreas Noeth ,
Paul Muralt ,
Alexander K. Tagantsev  and
Nava Setter
Tomoaki Yamada
Affiliation:
tomoaki.yamada@epfl.ch, Swiss Federal Institute of Technology, EPFL, Ceramics Laboratory, STI-IMX-LC, MXD 210, Station 12, Lausanne, VD, CH-1015, Switzerland, +41 21 693 4952, +41 21 693 5810
Vladimir O. Sherman
Affiliation:
vladimir.cherman@epfl.ch, Swiss Federal Institute of Technology, EPFL, Ceramics Laboratory, Lausanne, CH-1015, Switzerland
Andreas Noeth
Affiliation:
andreas.noeth@epfl.ch, Swiss Federal Institute of Technology, EPFL, Ceramics Laboratory, Lausanne, CH-1015, Switzerland
Paul Muralt
Affiliation:
Paul.Muralt@epfl.ch, Swiss Federal Institute of Technology, EPFL, Ceramics Laboratory, Lausanne, CH-1015, Switzerland
Alexander K. Tagantsev
Affiliation:
alexander.tagantsev@epfl.ch, Swiss Federal Institute of Technology, EPFL, Ceramics Laboratory, Lausanne, CH-1015, Switzerland
Nava Setter
Affiliation:
nava.setter@epfl.ch, Swiss Federal Institute of Technology, EPFL, Ceramics Laboratory, Lausanne, CH-1015, Switzerland
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Abstract

Ba0.3Sr0.7TiO3 (BST) thin film composite structures were fabricated by means of a selective epitaxial growth process. The epitaxial growth of BST on SrRuO3 electrode surface was selectively achieved at 450∼485°C using a prepatterned ultra-thin amorphous BST layer that locally prevented crystallization. This self build-up mechanism resulted in a columnar composite structure, where epitaxial and amorphous BST columns are electrically connected in parallel. The epitaxial BST showed a high permittivity and a high tunability, whereas the amorphous BST showed a significantly lower permittivity and a very weak tunable behavior. The effective permittivity of the composite capacitors decreased linearly upon increasing the amorphous BST concentration q, while the tunability stayed fairly unchanged until q reached 70%, which agrees with the theoretical ferroelectric/dielectric parallel composite model. The results also give indirect evidence of a good separation between both BST phases.

Keywords

ferroelectricfilmcomposite
Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 928: Symposium GG – Current and Future Trends of Functional Oxide Films , 2006 , 0928-GG01-03
Copyright
Copyright © Materials Research Society 2006

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References

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