In-plane dielectric properties of epitaxial Ba 0.7Sr 0.3TiO 3 thin films grown on GaAs for tunable device application

We have epitaxially deposited ferroelectric Ba0.7Sr0.3TiO3(BST) thin films grown on GaAs substrate via SrTiO3buffer 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.