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Enhanced Dielectric Properties Of Compositionally Modified BST Based Thin Films For Voltage Tunable Microwave Devices

Published online by Cambridge University Press:  01 February 2011

M. W. Cole ,
W. D. Nothwang ,
C. Hubbard ,
E. Ngo  and
M. Ervin
M. W. Cole
Affiliation:
U.S. Army Research Laboratory, Weapons and Materials Research Directorate, Aberdeen Proving Ground, MD 21005, U.S.A., (410) 306–0747mcole@arl.army.mil
W. D. Nothwang
Affiliation:
U.S. Army Research Laboratory, Weapons and Materials Research Directorate, Aberdeen Proving Ground, MD 21005, U.S.A., (410) 306–0747mcole@arl.army.mil
C. Hubbard
Affiliation:
U.S. Army Research Laboratory, Weapons and Materials Research Directorate, Aberdeen Proving Ground, MD 21005, U.S.A., (410) 306–0747mcole@arl.army.mil
E. Ngo
Affiliation:
U.S. Army Research Laboratory, Weapons and Materials Research Directorate, Aberdeen Proving Ground, MD 21005, U.S.A., (410) 306–0747mcole@arl.army.mil
M. Ervin
Affiliation:
U.S. Army Research Laboratory, Weapons and Materials Research Directorate, Aberdeen Proving Ground, MD 21005, U.S.A., (410) 306–0747mcole@arl.army.mil
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Abstract

In this work, material compositional design and optimized film processing methods, were employed to simultaneously lower the dielectric loss and enhance the dielectric tunability of Ba0.6Sr0.4TiO3 (BST) based thin films without compromising the device impedance matching (εr<500) and device control voltage (<10 V) requirements. The films compositional design was achieved by Mg doping BST from 3 to 10 mol % via the metalorganic solution deposition (MOSD) technique and post-deposition annealing in an oxygen ambience. The films dielectric loss at these doping levels was identical, tanδ ∼0.007 and the permittivity values ranged from 339 to 220. Device quality values of tunability, 40 and 32 %, for the 3 and 7 mol% doped BST films, respectively, were achieved by elevating the applied bias to 474 kV/cm. This device quality tuning is compatible with voltage requirements of current semiconductor based systems. The results suggest that the low level acceptor doping from 3 to 7 mol%, optimized precursor solution concentration (0.43 M), and oxygenated post-deposition thermal processing were found to work in concert to lower dielectric loss, limit defect density concentration, optimize film microstructure, and eliminate undesirable film/electrode interfacial phases. The enhanced dielectric and insulating properties of the 3–7 mol% Mg doped BST thin films make them excellent candidates for integration into tunable devices.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 784: Symposium C – Ferroelectric Thin Films XII , 2003 , C5.6
Copyright
Copyright © Materials Research Society 2004

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References

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