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Title: Dielectric properties of <001>-oriented Ba{sub 0.6}Sr{sub 0.4}TiO{sub 3} thin films on polycrystalline metal tapes using biaxially oriented MgO/{gamma}-Al{sub 2}O{sub 3} buffer layers

Abstract

We report the growth of <001>-oriented Ba{sub 0.6}Sr{sub 0.4}TiO{sub 3} (BST) thin films on polycrystalline Ni-alloy tapes by pulsed laser deposition using biaxially oriented, ion-beam-assisted deposited (IBAD) MgO and {gamma}-Al{sub 2}O{sub 3} buffer layers. Dielectric constant values of our BST films were up to {approx}85% of those in the epitaxial films prepared under similar conditions on single-crystal MgO substrates. No significant dispersion of the dielectric constant was observed for frequencies from 100 Hz to 1 MHz. These results demonstrate the versatility of using IBAD-textured MgO and {gamma}-Al{sub 2}O{sub 3} buffer layers to integrate highly oriented good-quality BST films with nonsingle-crystalline substrates.

Authors:
; ; ; ;  [1]
  1. Materials Science and Technology Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)
Publication Date:
OSTI Identifier:
20778681
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 88; Journal Issue: 6; Other Information: DOI: 10.1063/1.2173232; (c) 2006 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ALUMINIUM OXIDES; BARIUM COMPOUNDS; BUFFERS; DIELECTRIC MATERIALS; ENERGY BEAM DEPOSITION; EPITAXY; HZ RANGE; ION BEAMS; LASER RADIATION; LAYERS; MAGNESIUM OXIDES; MONOCRYSTALS; NICKEL ALLOYS; PERMITTIVITY; POLYCRYSTALS; PULSED IRRADIATION; STRONTIUM TITANATES; SUBSTRATES; THIN FILMS

Citation Formats

Choi, W., Kang, B.S., Jia, Q.X., Matias, V., and Findikoglu, A.T.. Dielectric properties of <001>-oriented Ba{sub 0.6}Sr{sub 0.4}TiO{sub 3} thin films on polycrystalline metal tapes using biaxially oriented MgO/{gamma}-Al{sub 2}O{sub 3} buffer layers. United States: N. p., 2006. Web. doi:10.1063/1.2173232.
Choi, W., Kang, B.S., Jia, Q.X., Matias, V., & Findikoglu, A.T.. Dielectric properties of <001>-oriented Ba{sub 0.6}Sr{sub 0.4}TiO{sub 3} thin films on polycrystalline metal tapes using biaxially oriented MgO/{gamma}-Al{sub 2}O{sub 3} buffer layers. United States. doi:10.1063/1.2173232.
Choi, W., Kang, B.S., Jia, Q.X., Matias, V., and Findikoglu, A.T.. Mon . "Dielectric properties of <001>-oriented Ba{sub 0.6}Sr{sub 0.4}TiO{sub 3} thin films on polycrystalline metal tapes using biaxially oriented MgO/{gamma}-Al{sub 2}O{sub 3} buffer layers". United States. doi:10.1063/1.2173232.
@article{osti_20778681,
title = {Dielectric properties of <001>-oriented Ba{sub 0.6}Sr{sub 0.4}TiO{sub 3} thin films on polycrystalline metal tapes using biaxially oriented MgO/{gamma}-Al{sub 2}O{sub 3} buffer layers},
author = {Choi, W. and Kang, B.S. and Jia, Q.X. and Matias, V. and Findikoglu, A.T.},
abstractNote = {We report the growth of <001>-oriented Ba{sub 0.6}Sr{sub 0.4}TiO{sub 3} (BST) thin films on polycrystalline Ni-alloy tapes by pulsed laser deposition using biaxially oriented, ion-beam-assisted deposited (IBAD) MgO and {gamma}-Al{sub 2}O{sub 3} buffer layers. Dielectric constant values of our BST films were up to {approx}85% of those in the epitaxial films prepared under similar conditions on single-crystal MgO substrates. No significant dispersion of the dielectric constant was observed for frequencies from 100 Hz to 1 MHz. These results demonstrate the versatility of using IBAD-textured MgO and {gamma}-Al{sub 2}O{sub 3} buffer layers to integrate highly oriented good-quality BST films with nonsingle-crystalline substrates.},
doi = {10.1063/1.2173232},
journal = {Applied Physics Letters},
number = 6,
volume = 88,
place = {United States},
year = {Mon Feb 06 00:00:00 EST 2006},
month = {Mon Feb 06 00:00:00 EST 2006}
}
  • Perovskite Ba{sub 0.6}Sr{sub 0.4}TiO{sub 3} (BST) thin films have been grown on Al{sub 2}O{sub 3}(0001) substrates without/with inserting an ultrathin TiO{sub x} seeding layer by rf magnetron sputtering. X-ray diffraction and pole figure studies reveal that the film with the TiO{sub x} layer (12-A-thick) is highly oriented along the (111) direction and exhibits a good in-plane relationship of BST(111)||Al{sub 2}O{sub 3}(0001). The high frequency dielectric measurements demonstrate that the complex permittivity ({epsilon}={epsilon}{sup '}-j{epsilon}{sup ''}) is well described by a Curie-von Scheidler dispersion with an exponent of 0.40. The resulting epitaxial BST films show high permittivity ({approx}428) and tunability ({approx}41%, atmore » 300 kV/cm and 40 GHz) and their microwave properties (1-40 GHz) potentially could be made suitable for tunable devices.« less
  • We deposited epitaxial Ba{sub 0.4}Sr{sub 0.6}TiO{sub 3} (BST) films via laser ablation on MgO and LaAlO{sub 3} (LAO) substrates for tunable microwave devices. Postdeposition anneals ({approx}1100 degree sign C in O{sub 2}) improved the morphology and overall dielectric properties of films on both substrates, but shifted the temperature of maximum dielectric constant (T{sub max}) up for BST/LAO and down for BST/MgO. These substrate-dependent T{sub max} shifts had opposite effects on the room-temperature dielectric properties. Overall, BST films on MgO had the larger maximum dielectric constant ({epsilon}/{epsilon}{sub 0}{>=}6000) and tunability ({delta}{epsilon}/{epsilon}{>=}65%), but these maxima occurred at 227 K. 30 GHz phasemore » shifters made from similar films had figures of merit (ratio of maximum phase shift to insertion loss) of {approx}45 degree sign /dB and phase shifts of {approx}400 degree sign under 500 V ({approx}13 V/{mu}m) bias, illustrating their utility for many frequency-agile microwave devices. (c) 2000 American Institute of Physics.« less
  • We report a systematic study of the structural and dielectric properties of barium strontium titanate, Ba{sub 0.6}Sr{sub 0.4}TiO{sub 3} (BST-0.4), films grown by pulsed laser deposition on LaAlO{sub 3} and MgO substrates. By optimizing the processing conditions, choosing appropriate substrate materials, and constructing layered architectures, we have successfully deposited BST-0.4 films on both LaAlO{sub 3} and MgO substrates with large dielectric nonlinearity and low dielectric loss. X-ray diffraction and transmission electron microscopy analyses reveal that the dielectric tunability and the dielectric loss are closely related to the crystallinity of the BST-0.4 films. We have also observed that a small variationmore » of D value, defined as the ratio of in-plane lattice constant/out-of-plane lattice constant, can result in a significantly large change of dielectric properties of the BST films.« less
  • Mist plasma evaporation (MPE) technique has been developed to deposit Ba{sub 0.6}Sr{sub 0.4}TiO{sub 3} (BST) thin films on SiO{sub 2}/Si and Pt/Ti/SiO{sub 2}/Si substrates at atmospheric pressure using metal nitrate aqueous solution as precursor. MPE is characterized by the injection of liquid reactants into thermal plasma where the source materials in the droplets are evaporated by the high temperature of the thermal plasma. Nanometer-scale clusters are formed in the tail flame of the plasma, and then deposited and rearranged on the substrate at a lower temperature. Due to the high temperature annealing process of the thermal plasma before deposition, well-crystallizedmore » BST films were deposited at substrate temperature of 630 deg. C. The dielectric constant and dielectric loss of the film at 100 kHz are 715 and 0.24, respectively. Due to the good crystallinity of the BST films deposited by MPE, high dielectric tunability up to 39.3% is achieved at low applied electric field of 100 kV cm{sup -1}.« 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