Relative dielectric constant of epitaxial BaTiO3 thin films in the GHz frequency range

The relative dielectric constant of epitaxial BaTiO3 thin films deposited on MgO was determined over the frequency range from 0.05 to 40.05 GHz. Coplanar stripline waveguides were formed on the BaTiO3 films and the dielectric constant was determined by matching the reflection (S11-) parameter by measurement with that by simulation. The dielectric constants were ∼2200 and ∼500 at <1 and 40 GHz, respectively. The frequency response of the dielectric constant is well described by a Curie–von Schweidler power law with an exponent of 0.29. The effective index of the coplanar stripline structure on the BaTiO3 film and MgO substrate was 3.6.