Modified Ba(1-x)Sr(x)TiO3 Thin Films for Tunable Device Applications
Final rept. May 2000-Nov 2001
ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH DIRECTORATE
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Pure and La doped Ba0.6Sr0.4TiO3 BST thin films were fabricated via the metalorganic solution deposition technique using carboxylate-alkoxide precursors on Pt-Si substrates. The La doping concentration, from 0-10 mole-percent, was found to have a strong influence on the 750 deg C post deposition annealed films material properties. All films possessed a nontextured polycrystalline microstructure with no evidence of secondary phase formation. The pure and 1 mole-percent La doped films exhibited a uniform microstructure suggestive of a fully developed film at this annealing temperature. Improved dielectric and insulating properties were achieved for the 1 mole-percent La doped BST thin films with respect to that of undoped BST films. The 1 mole-percent La doped EST film exhibited a lower dielectric constant 283 vs. 450 and enhanced resistivity 31.4 x 10 exp 13 Omega-cm vs. 0.04 x 10exp 13 Omega-cm with respect to that of undoped BST films. The loss tangent and tunability at 100 kHz of the 1 mole-percent La doped BST films were 0.019 and 21 at E 300 kVcm, respectively. Films doped at concentrations between 5 and 10 mole-percent possessed under developed microstructures, suggesting that higher annealing temperatures andor longer annealing times are required. The single phase structure of the 5 and 10 mole-percent La doped BST films, combined with the beneficial influence of the 1 mole-percent La doping on the BST films dielectric and insulating properties, suggest potential for further enhancement of the films material properties after optimization of the thermal treatments for the 5 and 10 mole-percent La doped BST thin films.
- Inorganic Chemistry
- Electrical and Electronic Equipment