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

Published

December 31, 1995

Author(s)

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

Abstract

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 Ba_xSr_1-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 C^3/2(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.

Citation

Integrated Ferroelectrics

Volume

6

Pub Type

Journals

Keywords

dielectric films, GHz regime, microwave devices

Citation

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 April 25, 2024)