Investigation of Barium Stannate Titanate Thin Films for Tunable Microwave Applications

Abstract

Barium stannate titanate Ba(Sn _0.15 Ti _0.85 )O ₃ (BTS) thin films have been investigated as a prospective material for tunable microwave applications. The thin films were fabricated by sol-gel method on (100) MgAl ₂ O ₄ single-crystal substrates. The influence of post-annealing on the structure and tunable dielectric properties of the thin films was studied. Using interdigital capacitors with Au electrodes on thin films, the dielectric constant and loss tangent were measured as a function of electric filed and temperature at 1 MHz. A tunability of 28.86% at E _max = 80 kV/cm and a loss tangent of 0.016 have been achieved for the sample annealed at 1000°C, measured at 1 MHz and room temperature. In addition, BTS films were also characterized at microwave frequencies up to 10 GHz. A capacitance change of 15.19% was observed at the frequency of 5 GHz with an applied electric field of 80 kV/cm.

Keywords:

• Thin films
• Sol-gel chemistry
• Dielectric properties
• Microwave properties

Acknowledgments

This research was supported by the Ministry of Sciences and Technology of China through 973-project under grant 2009CB623302, Specialized Research Fund for the Doctoral Program of Higher Education (SRFDP20060247003), the Cultivation Fund of the Key Scientific and Technical Innovation Project, Ministry of Education of China (NO.707024).