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Thin Film Multilayer Conductor/Ferroelectric Tunable Microwave Components for Communication ApplicationsHigh Temperature Superconductor/Ferroelectric (HTS/FE ) thin film multilayered structures deposited onto dielectric substrates are currently being investigated for use in low loss, tunable microwave components for satellite and ground based communications. The main goal for this technology is to achieve maximum tunability while keeping the microwave losses as low as possible, so as to avoid performance degradation when replacing conventional technology (e.g., filters and oscillators) with HTS/FE components. Therefore, for HTS/FE components to be successfully integrated into current working systems, full optimization of the material and electrical properties of the ferroelectric films, without degrading those of the HTS film; is required. Hence, aspects such as the appropriate type of ferroelectric and optimization of the deposition conditions (e.g., deposition temperature) should be carefully considered. The tunability range as well as the microwave losses of the desired varactor (i.e., tunable component) are also dependent on the geometry chosen (e.g., parallel plate capacitor, interdigital capacitor, coplanar waveguide, etc.). In addition, the performance of the circuit is dependent on the location of the varactor in the circuit and the biasing circuitry. In this paper, we will present our results on the study of the SrTiO3/YBa2Cu3O(7-delta)/LaAl03 (STO/YBCO/LAO) and the Ba(x)Sr(1-x)TiO3/YBa2Cu3O(7-delta)/LaAl03(BSTO/YBCO/ILAO) HTS/FE multilayered structures. We have observed that the amount of variation of the dielectric constant upon the application of a dc electric field is closely related to the microstructure of the film. The largest tuning of the STO/YBCO/LAO structure corresponded to single-phased, epitaxial STO films deposited at 800 C and with a thickness of 500 nm. Higher temperatures resulted in interfacial degradation and poor film quality, while lower deposition temperatures resulted in films with lower dielectric constants, lower tunabilities, and higher losses. For STO/LAO multilayer structures having STO film of similar quality we have observed that interdigital capacitor configurations allow for higher tunabilities and lower losses than parallel plate configurations, but required higher dc voltage. Results on the use of these geometries in working microwave components such as filters and stabilizing resonators for local oscillators (LO) will be discussed.
Document ID
19970021694
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Miranda, Felix A. (NASA Lewis Research Center Cleveland, OH United States)
Romanofsky, Robert R. (NASA Lewis Research Center Cleveland, OH United States)
VanKeuls, Frederick W. (NASA Lewis Research Center Cleveland, OH United States)
Mueller, Carl H. (SCT Golden, CO United States)
Treece, Randolph E. (SCT Golden, CO United States)
Rivkin, Tania V. (SCT Golden, CO United States)
Date Acquired
September 6, 2013
Publication Date
May 1, 1997
Subject Category
Solid-State Physics
Report/Patent Number
E-10695-1
NASA-TM-107456
NAS 1.15:107456
Meeting Information
Meeting: Integrated Ferroelectrics
Location: Santa Fe, New Mexico
Country: United States
Start Date: March 2, 1997
End Date: March 5, 1997
Sponsors: Colorado Univ.
Accession Number
97N22592
Funding Number(s)
PROJECT: RTOP 632-50-5D
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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