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Dielectric properties of epitaxial KNbO3 ferroelectric thin films

Published online by Cambridge University Press:  31 January 2011

Soma Chattopadhyay
Affiliation:
Department of Materials Science and Engineering and Materials Research Center, Northwestern University, Evanston, Illinois 60208
B. M. Nichols
Affiliation:
Department of Materials Science and Engineering and Materials Research Center, Northwestern University, Evanston, Illinois 60208
Jin-Ha Hwang
Affiliation:
Department of Materials Science and Engineering and Materials Research Center, Northwestern University, Evanston, Illinois 60208
T. O. Mason
Affiliation:
Department of Materials Science and Engineering and Materials Research Center, Northwestern University, Evanston, Illinois 60208
B. W. Wessels
Affiliation:
Department of Materials Science and Engineering and Materials Research Center, Northwestern University, Evanston, Illinois 60208
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Abstract

The dielectric response of KNbO3 epitaxial ferroelectric thin films was measured as a function of bias, frequency, and temperature. Thin films with a thickness of 80 to 350 nm were deposited on spinel substrates by low-pressure metalorganic chemical vapor deposition. Bias dependence measurements showed hysteresis in the dielectric response. The dielectric constant decreased with bias, and the tunability was calculated to be between 35% and 42% for an applied field of 7 MV/cm. The frequency dependence of the dielectric constant followed a power law. A pronounced thickness effect was observed in the dielectric response, especially at the Curie temperature. With decreasing thickness, the dielectric constant and the loss tangent decreased. A diffuse ferroelectric phase transition was observed for films with a thickness less than 350 nm.

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Rapid Communications
Copyright
Copyright © Materials Research Society 2002

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