Accession Number:

ADP013342

Title:

Investigations on Sol-Gel Derived Ba(0.5)Sr(0.5)Ti(1-Delta)Mn(Delta)O3 (Delta = 0.0 to 5.0 at %) Thin Films for Phase Shifter Applications

Descriptive Note:

Conference proceedings

Corporate Author:

PUERTO RICO UNIV SAN JUAN DEPT OF PHYSICS

Report Date:

2003-04-03

Pagination or Media Count:

12.0

Abstract:

Highly 100 oriented Ba0.5Sr0.5Ti1-deltaMndeltaO3 thin films were deposited on 100 LaAlO3 LAO substrate by sol-gel technique. We have studied systematically the effect of Mn doping on the degree of texturing, surface morphology, dielectric properties and phase transition behavior of barium strontium titanate BST thin films. Up to 3 at Mn doping the degree of 100 texturing and grain size of BST 5050 thin films were markedly improved, which led to an increased tunability from 29 undoped to 39 3 at Mn doped measured at 1 MHz and 2,34Vmicrometer bias field. The transition and Curie-Weiss temperaturs of BST 5050 thin films were found to be about 266 K and 185 K respectively, which confirmed the first order phase transition in the films. The variation of transition temperatures as a function of Mn doping contents in BST 5050 thin films were influenced by the variation of stress state and surface morphology modifications induced by Mn doping. The bias field dependence of the dielectric constant and loss tangents of undoped and Mn doped films were analyzed in terms of a model based on Devonshire theory. Phase shift measurements showed that the degree of phase shift increases from 239 deg to 337 deg with 0 to 3 at Mn doping. The insertion loss also increases from 5.4 dB undoped to 9.9 dB 3 at Mn doped with doping content so that there is no effective improvement in the kappa factor, which remains in the range of 33-44 degdB. Modification in surface morphology and film stoichiometry induced by Mn doping is thought to play significant role in observed phase shifter characteristics.

Subject Categories:

  • Physical Chemistry
  • Radiofrequency Wave Propagation

Distribution Statement:

APPROVED FOR PUBLIC RELEASE