Fabrication and characterization of electrically tunable high-T-c superconducting resonators incorporating barium strontium titanate as a tuning material

Abstract

We have made the electrically tunable microstrip resonators by using both high-ir, superconducting and dielectric films. The two-pole resonators employ a dielectric barium strontium titanate film on their centre in the form of flip chip. The superconducting YBa2Cu3Oy (YBCO) and dielectric Ba0.1Sr0.9TiO3 were deposited on the CeO2-buffered sapphire substrate and LaAlO3 substrate, respectively, by a pulsed laser deposition technique. Variations of the relative permittivity, epsilon(r), and dielectric loss tangent, tan delta, of the Ba0.1Sr0.9TiO3 Were Studied as a function of the applied de bias at liquid-nitrogen temperature. The tunability, defined as C-(0 V)/C-(100 V), and loss tangent of the resonators were measured to be similar to 1.9 and 1.5 x 10(-2) (at 100 V), respectively.