Microwave properties of BST and BST/BMT thin films grown on sapphire substrate by evanescent microwave probe

P. T. Joseph, Yi Chun Chen, Ying-hao Chu, Hsiu Fung Cheng*, Nyan Hwa Tai, I. Nan Lin

*Corresponding author for this work

Research output: Contribution to journalConference article

2 Scopus citations

Abstract

Thin films of BaxSr1-xTiO3 (BST) serial materials have the advantages of adjustable tunability and are good candidates for the application in DRAM and microwave devices. However, these films usually have loss tangent higher than the order of 0.01 at microwave frequencies. To improve the crystal structures and suppress the microwave losses, an interlayer material with good microwave properties can be used. In this present work, a low loss Ba(Mg1/3Ta2/3)O3 (BMT) thin buffer layer with varying thickness and its effect on the microwave properties of Ba 0.4Sr0.6TiO3 thin films is investigated. Moreover, to overcome the spatial limit in the traditional microwave measurement, a novel technique, evanescent microwave probe (EMP) method, is used to directly probe the microwave dielectric properties of the films. This technique also provides the capability to study the dielectric mechanism in micro-scale region. Pulsed laser deposition technique was used to synthesize thin films. The films shows (111) preferably oriented growth of BST films with the introduction of BMT layer for the films grown on sapphire substrates. As the thickness of BMT increases, this behavior is more obvious. The microwave dielectric constants (ε) and dielectric losses (tan δ) of the films grown on sapphire substrates have been measured by EMP. The dielectric constants of BST thin films decrease monotonously with the increase of BMT thickness. In contrast, the tan δ shows a discontinuity variation when the BMT buffer layer is deposited for 10-20 minutes.

Original languageEnglish
Pages (from-to)45-50
Number of pages6
JournalIntegrated Ferroelectrics
Volume77
DOIs
StatePublished - 10 Apr 2006
EventSeventeenth International Symposium on Integrated Ferroelectrics, ISIF-17 - Shanghai, China
Duration: 17 Apr 200520 Apr 2005

Keywords

  • (BaSr)TiO thin films
  • Ba(Mg Ta)O buffer layer
  • Microwave dielectric properties
  • Pulsed laser deposition

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