Title :
Electrically tunable microwave devices prepared by rf-magnetron sputtering
Author :
Gibbons, B.J. ; Findikoglu, A.T. ; Jia, Q.X. ; Reagor, D.W.
Author_Institution :
Supercond. Technol. Center, Los Alamos Nat. Lab., NM, USA
Abstract :
In this work, we have used the Warren-Averbach method to analyze the x-ray diffraction patterns of several Ba0.6Sr0.4 TiO3 (BST) epitaxial thin films deposited via 90° off-axis rf-magnetron sputtering. This method allows for the determination of the coherent strains, incoherent strains, crystallite sizes, and defect densities in these films. Results indicate that for BST (60/40) films, the incoherent strain normal to the substrate is smaller on LAO compared to MgO for films 200 Å - 3000 Å thick. However, the opposite relationship holds for the coherent strains. The thickest films showed dielectric constants of 1350 and 925 on MgO and LAO, respectively (at 1 MHz). All showed dielectric loss on the order of 0.007 with the room temperature tunability being 3 times greater for the films on MgO. In-plane measurements of the coherent strain were also completed, showing good agreement with theoretical predictions of the effects of strain on the dielectric properties
Keywords :
X-ray diffraction; dielectric losses; ferroelectric capacitors; ferroelectric thin films; microwave devices; microwave materials; permittivity; sputter deposition; sputtered coatings; thin film capacitors; tuning; 200 to 3000 A; Ba0.6SrO4TiO3; Warren-Averbach method; capacitors; coherent strains; conformal mapping model; crystallite sizes; defect densities; dielectric constants; dielectric loss; electrically tunable microwave devices; epitaxial thin films; incoherent strains; lattice parameters; off-axis RF-magnetron sputtering; room temperature tunability; x-ray diffraction patterns; Binary search trees; Capacitive sensors; Dielectric losses; Dielectric substrates; Microwave devices; Pattern analysis; Sputtering; Strain measurement; Strontium; X-ray diffraction;
Conference_Titel :
Applications of Ferroelectrics, 2000. ISAF 2000. Proceedings of the 2000 12th IEEE International Symposium on
Conference_Location :
Honolulu, HI
Print_ISBN :
0-7803-5940-2
DOI :
10.1109/ISAF.2000.941541
