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Pulsed Laser Deposition of BaxSr1−xTiO3 Films on MgO, LaAlO3 and SrTiO3 for Tunable Microwave Applications

Published online by Cambridge University Press:  10 February 2011

Wontae Chang ,
James S. Horwitz ,
Won-Jeong Kim ,
Jeffrey M. Pond ,
Steven W. Kirchoefer ,
Charles M. Gilmore ,
Syed B. Qadri  and
Douglas B. Chrisey
Wontae Chang
Affiliation:
Institute for Materials Science, School of Engineering and Applied Science George Washington University, 725 23rd Street, NW, Washington, D.C. 20052
James S. Horwitz
Affiliation:
Naval Research Laboratory, 4555 Overlook Ave., SW, Washington, D.C. 20375
Won-Jeong Kim
Affiliation:
SFA Inc., 1401 McCormick Dr., Largo, AID 20774
Jeffrey M. Pond
Affiliation:
Naval Research Laboratory, 4555 Overlook Ave., SW, Washington, D.C. 20375
Steven W. Kirchoefer
Affiliation:
Naval Research Laboratory, 4555 Overlook Ave., SW, Washington, D.C. 20375
Charles M. Gilmore
Affiliation:
Institute for Materials Science, School of Engineering and Applied Science George Washington University, 725 23rd Street, NW, Washington, D.C. 20052 Naval Research Laboratory, 4555 Overlook Ave., SW, Washington, D.C. 20375
Syed B. Qadri
Affiliation:
Naval Research Laboratory, 4555 Overlook Ave., SW, Washington, D.C. 20375
Douglas B. Chrisey
Affiliation:
Naval Research Laboratory, 4555 Overlook Ave., SW, Washington, D.C. 20375
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Abstract

Single phase BaxSr1−xTiO3 (BST) films (∼0.5-7 μm thick) have been deposited onto single crystal substrates (MgO, LaAlO3, SrTiO3) by pulsed laser deposition. Silver interdigitated electrodes were deposited on top of the ferroelectric film. The room temperature capacitance and dielectric Q (1/tanδ) of the film have been measured as a function of electric field (≤80 kV/cm) at 1 - 20 GHz. The dielectric properties of the film are observed to strongly depend on substrate type and post-deposition processing. After annealing (≤1000° C), it was observed that the dielectric constant and % tuning decreased and the dielectric Q increased for films deposited onto MgO, and the opposite effect was observed for films deposited onto LaA1O3. Presumably, this change in dielectric properties is due to the changes in film stress. Very thin (∼50 Å) amorphous BST films were successfully used as a stress-relief layer for the subsequently deposited crystalline BST (∼5000 Å) films to maximize % tuning and dielectric Q. Films have been deposited from stoichiometric targets and targets that have excess Ba and Sr. The additional Ba and Sr has been added to the target to compensate for deficiencies in Ba and Sr observed in the deposited BST (x=0.5) films. Films deposited from compensated targets have higher dielectric constants than films deposited from stoichiometric targets. Donor/acceptor dopants have also been added to the BST target (Mn, W, Fe ≤4 mol.%) to further improve the dielectric properties. The relationship between the dielectric constant, the dielectric Q, the change in dielectric constant with electric field is discussed.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 541: Symposium O – Ferroelectric Thin Films VII , 1998 , 693
Copyright
Copyright © Materials Research Society 1999

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References

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