skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: (YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}},Au)/SrTiO{sub 3}/LaAlO{sub 3} thin film conductor/ferroelectric coupled microstripline phase shifters for phased array applications

Abstract

We report on the design, fabrication, and testing of novel YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}}/SrTiO{sub 3}/LaAlO{sub 3} (YBCO/STO/LAO) and Au/SrTiO{sub 3}/LaAlO{sub 3} (Au/STO/LAO) coupled microstrip line phase shifters (CMPS). These CMPS were tested at frequencies within the Ku and K bands (12{endash}20 GHz), at temperatures from 24 to 77 K, and at dc voltages (V{sub dc}) from zero to 350 V. A relative insertion phase shift ({Delta}{phi}) of 390{degree} was measured for an eight-element YBCO/STO/LAO CMPS at V{sub dc}=350V, 16 GHz, and 40 K. At 77 K, a {Delta}{phi}{approximately}260{degree} was obtained for the CMPS at the same bias and frequency. Both results correspond to an effective coupling length of 0.33 cm. At both temperatures, the phase shifter exhibits a figure of merit of {approximately}30{degree}/dB. To our knowledge, these are the best results published so far at these frequencies where miniaturization, insertion loss, and phase delay are key considerations. {copyright} {ital 1997 American Institute of Physics.}

Authors:
; ; ; ;  [1]; ; ; ;  [2]
  1. National Aeronautics and Space Administration, Lewis Research Center, Cleveland, Ohio 44135 (United States)
  2. SCT, Golden, Colorado 80401 (United States)
Publication Date:
OSTI Identifier:
552935
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 71; Journal Issue: 21; Other Information: PBD: Nov 1997
Country of Publication:
United States
Language:
English
Subject:
66 PHYSICS; 36 MATERIALS SCIENCE; SUPERCONDUCTING DEVICES; MICROWAVE POWER TRANSMISSION; HIGH-TC SUPERCONDUCTORS; PHASE SHIFT; LANTHANUM COMPOUNDS; STRONTIUM COMPOUNDS; GOLD; YTTRIUM COMPOUNDS; BARIUM COMPOUNDS; SUPERCONDUCTING FILMS; YTTRIUM OXIDES; BARIUM OXIDES; COPPER OXIDES; STRONTIUM OXIDES; TITANIUM OXIDES; LANTHANUM OXIDES; FERROELECTRIC MATERIALS; TEMPERATURE DEPENDENCE; GHZ RANGE 01-100

Citation Formats

Van Keuls, F.W., Romanofsky, R.R., Bohman, D.Y., Winters, M.D., Miranda, F.A., Mueller, C.H., Treece, R.E., Rivkin, T.V., and Galt, D.. (YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}},Au)/SrTiO{sub 3}/LaAlO{sub 3} thin film conductor/ferroelectric coupled microstripline phase shifters for phased array applications. United States: N. p., 1997. Web. doi:10.1063/1.120251.
Van Keuls, F.W., Romanofsky, R.R., Bohman, D.Y., Winters, M.D., Miranda, F.A., Mueller, C.H., Treece, R.E., Rivkin, T.V., & Galt, D.. (YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}},Au)/SrTiO{sub 3}/LaAlO{sub 3} thin film conductor/ferroelectric coupled microstripline phase shifters for phased array applications. United States. doi:10.1063/1.120251.
Van Keuls, F.W., Romanofsky, R.R., Bohman, D.Y., Winters, M.D., Miranda, F.A., Mueller, C.H., Treece, R.E., Rivkin, T.V., and Galt, D.. 1997. "(YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}},Au)/SrTiO{sub 3}/LaAlO{sub 3} thin film conductor/ferroelectric coupled microstripline phase shifters for phased array applications". United States. doi:10.1063/1.120251.
@article{osti_552935,
title = {(YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}},Au)/SrTiO{sub 3}/LaAlO{sub 3} thin film conductor/ferroelectric coupled microstripline phase shifters for phased array applications},
author = {Van Keuls, F.W. and Romanofsky, R.R. and Bohman, D.Y. and Winters, M.D. and Miranda, F.A. and Mueller, C.H. and Treece, R.E. and Rivkin, T.V. and Galt, D.},
abstractNote = {We report on the design, fabrication, and testing of novel YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}}/SrTiO{sub 3}/LaAlO{sub 3} (YBCO/STO/LAO) and Au/SrTiO{sub 3}/LaAlO{sub 3} (Au/STO/LAO) coupled microstrip line phase shifters (CMPS). These CMPS were tested at frequencies within the Ku and K bands (12{endash}20 GHz), at temperatures from 24 to 77 K, and at dc voltages (V{sub dc}) from zero to 350 V. A relative insertion phase shift ({Delta}{phi}) of 390{degree} was measured for an eight-element YBCO/STO/LAO CMPS at V{sub dc}=350V, 16 GHz, and 40 K. At 77 K, a {Delta}{phi}{approximately}260{degree} was obtained for the CMPS at the same bias and frequency. Both results correspond to an effective coupling length of 0.33 cm. At both temperatures, the phase shifter exhibits a figure of merit of {approximately}30{degree}/dB. To our knowledge, these are the best results published so far at these frequencies where miniaturization, insertion loss, and phase delay are key considerations. {copyright} {ital 1997 American Institute of Physics.}},
doi = {10.1063/1.120251},
journal = {Applied Physics Letters},
number = 21,
volume = 71,
place = {United States},
year = 1997,
month =
}
  • The defect structure of epitaxial, {ital c}-oriented Bi{sub 2}Sr{sub 2}Ca{sub {ital n}{minus}1}Cu{sub {ital n}}O{sub 4+2{ital n}+{delta}} (BSCCO) thin films grown by dc-sputtering and layer-by-layer MBE on SrTiO{sub 3} and LaAlO{sub 3} single crystal substrates was investigated by high-resolution transmission electron microscopy (HRTEM). Particular emphasis was put on the structure of the film/substrate interface. The films grown by dc-sputtering show a rather perfect structure involving a regular stacking of the unit cells. In spite of this regularity, there are many defects, such as twins, chemical stacking faults, and precipitates, as well as interfacial dislocations accommodating the film/substrate lattice misfit. The MBE-grownmore » films contain twins and interfacial dislocations, but most prominent are precipitates of various size and rather high number density. Composition and structure of the precipitates were analyzed. Interfacial dislocations were found to be located in the films at a distance of up to 3 nm from the film/substrate interface. The experiments showed that the quality of the film/substrate interface in MBE-grown films is considerably higher with respect to smoothness, sharpness and regularity, if the layer-by-layer MBE process starts with a Sr{endash}O layer instead of a Bi{endash}O layer. This observation is in correspondence to the observed interface structure of the dc-sputtered films, where the first film layer was a Sr{endash}O layer, not a Bi{endash}O layer, in spite of the films being sputtered from a composite target. A structure model of the Bi{sub 2}Sr{sub 2}Ca{sub {ital n}{minus}1}Cu{sub {ital n}}O{sub 4+2{ital n}+{delta}}/(100)SrTiO{sub 3} interface is proposed. The prolonged MBE process was shown to imply a chemical interaction between the SrTiO{sub 3} substrate and the growing film, resulting in the formation of Sr-rich phases in the near-interface substrate regions. {copyright} {ital 1996 Materials Research Society.}« less
  • Dielectric Ba{sub 0.6}Sr{sub 0.4}TiO{sub 3} thin films were epitaxially grown on (001) MgO by using pulsed laser ablation. Microstructure studies from x-ray diffraction and electron microscopy suggest that the as-grown films are c-axis oriented with an interface relationship of <100>BSTO//<100>MgO. A room temperature coupled microwave phase shifter has been developed with a phase shift near 250{sup o} at 23.675 GHz under an electrical field of 40 V/{mu}m and a figure of merit of {approx}53{sup o}/dB. The performance of the microwave phase shifter based on the epitaxial Ba{sub 0.6}Sr{sub 0.4}TiO{sub 3} thin films on (001) MgO is close to that neededmore » for practical applications in wireless communications.« less
  • The microstructure of YBa{sub 2}Cu{sub 3}O{sub 7{minus}}{sub {delta}} thin films deposited on (001)LaAlO{sub 3} substrates by a laser ablation process has been investigated by scanning electron microscopy, x-ray diffraction, and cross-sectional transmission electron microscopy. Adjacent to the substrate, the film is entirely oriented with the {ital c}-axis perpendicular to the surface. At a thickness of about 0.4 {mu}m, the occurrence of 90{degree} boundaries brings about a transition to grains with their {ital c}-axes parallel to the surface (aligned along the (100) and (010) directions of the pseudocubic LaAlO{sub 3} substrate). This transition is discussed in terms of the crystal growthmore » anisotropy and the retained strain that may precipitate the transition.« less
  • The correlations between structural quality and superconducting behavior in 1000-A-thick Ba{sub 2}YCu{sub 3}O{sub 7{minus}{delta}} (BYCO) films grown on LaAlO{sub 3}(100) from the coevaporation of BaF{sub 2}, Y, and Cu, followed by an optimized {ital ex} {ital situ} annealing process are reported. Epitaxial films with smooth, laminar morphology and excellent crystallinity can be grown to have critical current density {ital J}{sub {ital c}} values nearly identical to single crystals. This finding contrasts with the typical observation that {ital J}{sub {ital c}} values in thin films of BYCO are very high compared to those of single crystals. This is attributed to amore » greater density of flux pinning sites due to structural defects within the films. The most crystalline films presented here have penetration length {lambda}{similar to}2000 A with temperature dependencies described well by the Bardeen--Cooper--Schrieffer (BCS) theory. Material disorder of two types can be controlled by the high-temperature stage {ital T}{sub {ital a}} of the annealing process. The first type is point defects and dislocations the same size or smaller than the coherence length {xi}{sub {ital ab}}, which Rutherford backscattering/channeling suggests decrease in number with increasing {ital T}{sub {ital a}}. The second is crevices, pinholes, and microcracks, which are at least one to two orders of magnitude larger than {xi}{sub {ital ab}}. At {ital T}{sub {ital a}} {lt} 850 {degree}C, crevices, which create areas of nonuniform thickness, occur due to incomplete epitaxial growth and correlate with the presence of weak links. Hence film resistivity is high, {ital T}{sub {ital c}} is low, and {lambda} is large.« less
  • A characteristic feature of epitaxial (110) thin films of YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} and PrBa{sub 2}Cu{sub 3}O{sub 7{minus}{ital x}} on (110)SrTiO{sub 3} substrates is that the films have a tendency to crack along the (001) planes. We have studied the crack spacing as a function of deposition temperature and film thickness. The experimental data have been found to be in excellent agreement with a theoretical analysis of the crack spacings in brittle films. The study has allowed us to determine the critical thickness below which no cracks are expected to form as a function of temperature for (110) films ofmore » YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}}, PrBa{sub 2}Cu{sub 3}O{sub 7{minus}{ital x}}, and YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}}/ PrBa{sub 2}Cu{sub 3}O{sub 7{minus}{ital x}} bilayers.« less