Title: Ferroelectric thin films working at microwave frequency for reconfigurable devices on silicon substrate: performances comparison between BST, PST

Authors: Freddy Ponchel; Denis Remiens; Areski Ghalem; Tuami Lasri

Addresses: IEMN – DOAE, MAMINA Group, CNRS-UMR 8520, Valenciennes Cedex 9, France ' IEMN – DOAE, MAMINA Group, CNRS-UMR 8520, Valenciennes Cedex 9, France ' IEMN – DOAE, MAMINA Group, CNRS-UMR 8520, Valenciennes Cedex 9, France ' IEMN, MITEC Group, CNRS-UMR8520, Villeneuve d'Ascq, France

Abstract: The dielectric microwave performance of BST and PST films is studied via tunability. The films are deposited onto silicon wafer with high resistivity using radio frequency magnetron sputtering with an in situ process for BST films and ex situ for PST films. In order to improve the crystalline quality of the films a buffer layer is introduced systematically. The films have a pure perovskite structure. The microwave test structures are coplanar line waveguides that give a complete microwave characterisation up to 67 GHz. The determination of the tunability properties at microwave frequency is obtained by measurements of the scattering parameters coupled with software, written by the authors, based on a two-dimensional vector finite element method. At 67 GHz, the BST tunability reaches a value of 29% with 30 V maximum applied voltage and the PST attains a value of 60% at the same condition. PST appears as a promising alternative material to BST for microwave tunable devices.

Keywords: ferroelectric thin films; sputtering; microwave frequency; dielectric microwave performance; tunability; reconfigurable devices; silicon wafers; crystalline quality; perovskite structure; coplanar line waveguides; 2D vector FEM; finite element method; BaSrTi03 thin films; BST thin films; PST thin films; Pb0.4Sr0.6TiO3 thin films.

DOI: 10.1504/IJMATEI.2014.066857

International Journal of Materials Engineering Innovation, 2014 Vol.5 No.4, pp.327 - 335

Received: 11 Sep 2013
Accepted: 12 Jan 2014
Published online: 26 Feb 2015 *

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