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Title: Laser Ablated and RF Sputtered BaTiO3 Thin Films for Use in Superconducting RF MEM Switches

Abstract

In this work an investigative study of the crystal structure of BaTiO3 thin films prepared using two techniques (laser ablation and RF magnetron sputtering) is presented. These films are to be used as the insulation layer in a capacitively shunted superconducting RF MEM switch with an insertion loss of better than 0.05 dB and an isolation of 30 dB at 3 GHz. Using X-Ray diffraction, the aim of the study is to compare the quality of the sputtered and laser ablated films produced, and study their effect on the RF and mechanical performance of the switch. The crystal structure is expected to have an effect on the effective dielectric constant of the films, which in turn will affect the electrical performance of the switch. This work will report on these results and serve to further enhance the electrical performance of our MEM switches.

Authors:
; ; ; ; ; ; ; ; ;  [1];  [1];  [2]; ;  [3]
  1. Florida International University (FAST Center), Miami, Fl. 33174 (United States)
  2. (United States)
  3. Florida Agricultural University, Tallahassee, Fl. 32307 (United States)
Publication Date:
OSTI Identifier:
20653231
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 711; Journal Issue: 1; Conference: CEC 2003: Cryogenic engineering and international cryogenic materials conference on advances in cryogenic engineering, Anchorage, AK (United States), 22-26 Sep 2003; Other Information: DOI: 10.1063/1.1774638; (c) 2004 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ABLATION; BARIUM COMPOUNDS; CRYSTAL STRUCTURE; GHZ RANGE 01-100; MAGNETRONS; MICROSTRUCTURE; PERMITTIVITY; SPUTTERING; SUPERCONDUCTING DEVICES; SWITCHES; THIN FILMS; TITANATES; X-RAY DIFFRACTION

Citation Formats

Hijazi, Y., Bogozi, A., Brzhezinskaya, M., Martinez, J., Noel, J., Lawrence, L., Fairweather, D., Vargas, J., Vlasov, Yu., Larkins, G., Hanna, D., Hanscom Airforce Base, Boston, Ma. 02173, Kennedy, R., and Stampe, P. Laser Ablated and RF Sputtered BaTiO3 Thin Films for Use in Superconducting RF MEM Switches. United States: N. p., 2004. Web. doi:10.1063/1.1774638.
Hijazi, Y., Bogozi, A., Brzhezinskaya, M., Martinez, J., Noel, J., Lawrence, L., Fairweather, D., Vargas, J., Vlasov, Yu., Larkins, G., Hanna, D., Hanscom Airforce Base, Boston, Ma. 02173, Kennedy, R., & Stampe, P. Laser Ablated and RF Sputtered BaTiO3 Thin Films for Use in Superconducting RF MEM Switches. United States. doi:10.1063/1.1774638.
Hijazi, Y., Bogozi, A., Brzhezinskaya, M., Martinez, J., Noel, J., Lawrence, L., Fairweather, D., Vargas, J., Vlasov, Yu., Larkins, G., Hanna, D., Hanscom Airforce Base, Boston, Ma. 02173, Kennedy, R., and Stampe, P. Mon . "Laser Ablated and RF Sputtered BaTiO3 Thin Films for Use in Superconducting RF MEM Switches". United States. doi:10.1063/1.1774638.
@article{osti_20653231,
title = {Laser Ablated and RF Sputtered BaTiO3 Thin Films for Use in Superconducting RF MEM Switches},
author = {Hijazi, Y. and Bogozi, A. and Brzhezinskaya, M. and Martinez, J. and Noel, J. and Lawrence, L. and Fairweather, D. and Vargas, J. and Vlasov, Yu. and Larkins, G. and Hanna, D. and Hanscom Airforce Base, Boston, Ma. 02173 and Kennedy, R. and Stampe, P.},
abstractNote = {In this work an investigative study of the crystal structure of BaTiO3 thin films prepared using two techniques (laser ablation and RF magnetron sputtering) is presented. These films are to be used as the insulation layer in a capacitively shunted superconducting RF MEM switch with an insertion loss of better than 0.05 dB and an isolation of 30 dB at 3 GHz. Using X-Ray diffraction, the aim of the study is to compare the quality of the sputtered and laser ablated films produced, and study their effect on the RF and mechanical performance of the switch. The crystal structure is expected to have an effect on the effective dielectric constant of the films, which in turn will affect the electrical performance of the switch. This work will report on these results and serve to further enhance the electrical performance of our MEM switches.},
doi = {10.1063/1.1774638},
journal = {AIP Conference Proceedings},
number = 1,
volume = 711,
place = {United States},
year = {Mon Jun 28 00:00:00 EDT 2004},
month = {Mon Jun 28 00:00:00 EDT 2004}
}
  • A micro-electro-mechanical (MEM) switch built on a superconducting microstrip filter will be utilized to investigate BaTiO 3 dielectric patches for functional switching points of contact. Actuation voltage resulting from the MEM switch provokes static friction between the bridge membrane and BaTiO 3 insulation layer. Furthermore, the dielectric patch crystal structure and roughness affect the ability of repetitively switching cycles and lifetime. We performed a series of experiments using different deposition methods and RF magnetron sputtering was found to be the best deposition process for the BaTiO 3 layer. The effect examination of surface morphology will be presented using characterization techniquesmore » as x-ray diffraction, SEM and AFM for an optimum switching device. The thin film is made of YBa 2Cu 3O 7 deposited on LaAlO 3 substrate by pulsed laser deposition. In our work, the dielectric material sputtering pressure is set at 9.5x10 -6 Torr. The argon gas is released through a mass-flow controller to purge the system prior to deposition. RF power is 85 W at a distance of 9 cm. The behavior of Au membranes built on ultimate BaTiO 3 patches will be shown as part of the results. These novel surface patterns will in turn be used in modelling other RF MEM switch devices such as distributed-satellite communication system operating at cryogenic temperatures.« less
  • KrF excimer laser ablation of an Y/sub 1/Ba/sub 2/Cu/sub 3/O/sub 7-//sub delta/ pellet in 0.1--0.2 Torr of O/sub 2/ ambient was used to deposit thin superconducting films onto SrTiO/sub 3/, yttria-stabilized zirconia (YSZ), and silicon substrates at 600--700 /sup 0/C. The as-deposited 1-..mu..m-thick films at 650--700 /sup 0/C substrate temperature were superconducting, without further high-temperature annealing. All films had a similar T/sub c/ onset of approx.92 K but different zero-resistance T/sub c/ of 90, 85, and 70 K for the films on SrTiO/sub 3/, YSZ, and Si substrates, respectively. Angular x-ray diffraction analysis showed that all the films were highlymore » oriented with the c axis perpendicular to their surface. Critical current densities at 77 K were about 40 000 and 10 000 A/cm/sup 2/ for the films on SrTiO/sub 3/ and YSZ, respectively. Smooth surface morphology was observed in all films, with occasional defects and cracks in the films on YSZ, which seems to explain the lower critical current in these films.« less
  • High quality, c-axis oriented thin films of semiconducting La{sub 2}CuO{sub 4} have been fabricated by pulsed laser-ablation deposition. Superconducting properties have been successfully induced in the films by a postdeposition, ex-situ static annealing process in a F{sub 2}/N{sub 2} gas mixture. The influence of the fluorination temperature on the structural, magnetic, and electronic properties of the resulting thin films has been examined in detail. X-ray data reveal that facile fluorination of the films proceeds via a complex, multistage process, often yielding to distinct La{sub 2}CuO{sub 4}-type phases. This phase segregation suggests a disproportionation process following fluorine uptake. Such a disproportionationmore » is subtly different from that found for oxygen excess La{sub 2}CuO{sub 4} in that for La{sub 2}CuO{sub 4+{delta}} the parent O{sub 4} and an oxygen rich (O{sub 4+{delta}}) phase are formed, but in the present system two fluorinated (i.e., oxidized) phases are formed. La{sub 2}CuO{sub 4} thin films fluorinated at a temperature of 150 C possess the highest values for both T{sub c} (onset) (ca. 38.5 K) and critical current density (>10{sup 6} A cm{sup {minus}2} at 4.2 K in zero magnetic field). Magnetic susceptibility data demonstrate that this fluorination methodology is of sufficient sensitivity to allow the controlled hole-doping of semiconducting La{sub 2}CuO{sub 4} thin films through to the high-temperature superconducting regime.« less
  • The preferred orientation of a series of laser deposited superconducting thin films of YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} on LaAlO{sub 3} substrate has been examined. X-ray measurements (pole figures, {chi}-scans, {omega}-scans, rocking curves) reveal an increasingly strong preferred orientation of the polycrystalline material with c-axes perpendicular to the substrate surface as deposition temperature increases. At low temperatures c-axes are predominantly parallel to the substrate surface. Characteristic parameters of the texture types were derived from those measurements. With higher temperatures twinning on (110) was observed. The different texture types are interpreted in terms of a layered film structure.
  • High-temperature superconducing Tl-Ca-Ba-Cu-O (TlCaBaCuO) thin films were fabricated by rf magnetron sputtering on strontium titanate (SrTiO{sub 3}) substrates. Thin films of 0.5--0.7-{mu}m thickness were deposited by pure argon sputtering from a single composite powder target of Tl{sub 2}Ca{sub 2}Ba{sub 2}Cu{sub 3}O{sub {ital x}} at an rf power of 250 W and a pressure of 5 mTorr. As-deposited thin films were sintered and annealed in a thallium-rich ambient to obtain superconductivity with a zero resistance temperature ({ital T}{sub {ital c}0}) at 107 K. X-ray diffraction results showed highly {ital c}-axis oriented films with Tl{sub 2}Ca{sub 2}Ba{sub 2}Cu{sub 3}O{sub {ital x}} (2223)more » and Tl{sub 2}Ca{sub 1}Ba{sub 2}Cu{sub 2}O{sub {ital x}} (2122) phases present. Auger electron spectroscopy survey and depth profiles were performed to determine the compositional uniformity and impurity contents of the thin films. X ray photoelectron spectroscopy high-resolution spectra were obtained at the surface, in the bulk, and near the interface with the substrate. Our XPS results support two possible mechanisms for the creation of holes in the TlCaBaCuO compound: (1) partial substitution of Ca{sup 2+} for Tl{sup 3+} and (2) charge transfer from Tl{sup 3+} to the CuO layers resulting in a valence of Tl between +3 and +1 states and the creation of holes in the CuO layers. In addition, a wet chemical etching process was developed for patterning the as-deposited TlCaBaCuO thin films. A 125-{mu}m-wide line was formed using standard photolithography and wet chemical etching which, after heat treatments, showed superconductivity with a {ital T}{sub {ital c}0} of 80 K.« less