In-plane dielectric properties of epitaxial Ba₀.₇Sr₀.₃TiO₃ thin films grown on GaAs for tunable device application

Abstract

We have epitaxially deposited ferroelectric Ba₀.₇Sr₀.₃TiO₃ (BST) thin films grown on GaAs substrate via SrTiO₃ buffer layer by laser molecular beam epitaxy. Structural characteristics of the heterostructure were measured by various techniques. The in-plane dielectric properties of the heteroepitaxial structure under different applying frequency were investigated from −190 to 90 °C, indicating Curie temperature of the BST film to be around 52 °C. At room temperature, the dielectric constant of the heterostructure under moderate dc bias field can be tuned by more than 30% and K factor used for frequency agile materials is found to be close to 8. Our results offer the possibility to combine frequency agile electronics of ferroelectric titanate with the high-performance microwave capabilities of GaAs for room temperature tunable device application