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A Model of Voltage-Dependent Dieletric Losses for Ferroelectric MMIC Devices



J. F. Scott, J. Price, James A. Beall, Ronald H. Ono, C. A. Paz de Araujo, L. D. McMillian


The use of high-dielectric films for microwave devices, especially phased-array radar systems, in the tens of GHz regime requires very low-loss (0.01 to 0.1) films. Unfortunately most ferroelectrics have losses that diverge (greater than unity) in this frequency range. We develop in the present study quantitative models for dielectric loss in both SrTiO3 and BaxSr1-xTiO3 (BST) that givedependence upon temperature, frequency, and especially voltage or field. In pute strontium titanate we find that loss is intrins with qualtiy factor Q greater than 1000; and a dramatic voltage dependence of tan δ is observed to fit the C3/2(V) dependence upon capacitance predicted for three-and four-phonon anharmonicity for voltages up to 5V (E = 250 kV/cm). In most barium strontiun titanate ceramic films the loss is extrinsic at 100 MHz, and the surface layer model of Neumann and Hofmann describes the dependence of tan δ upon thickness D rather well, with tan δ increasing from 0.001 at D=5 microns to 0.10 at 10 nm. Typical values at 250 nm are ca. 0.015.
Integrated Ferroelectrics


dielectric films, GHz regime, microwave devices


Scott, J. , Price, J. , Beall, J. , Ono, R. , Paz de Araujo, C. and McMillian, L. (1995), A Model of Voltage-Dependent Dieletric Losses for Ferroelectric MMIC Devices, Integrated Ferroelectrics (Accessed July 16, 2024)


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Created December 30, 1995, Updated October 12, 2021