Epitaxial growth of dielectric Ba0.6Sr0.4TiO3 thin film on MgO for room temperature microwave phase shifters

Dielectric ${\mathrm{Ba}}_{\mathrm{0.6}}{\mathrm{Sr}}_{\mathrm{0.4}}{\mathrm{TiO}}_{\mathrm{3}}$ thin films were epitaxially grown on (001) MgO by using pulsed laser ablation. Microstructure studies from x-ray diffraction and electron microscopy suggest that the as-grown films are c-axis oriented with an interface relationship of 〈100〉BSTO//〈100〉MgO. A room temperature coupled microwave phase shifter has been developed with a phase shift near $\text{250°}$ at 23.675 GHz under an electrical field of 40 V/μm and a figure of merit of $\text{∼53°/}\mathrm{dB}.$ The performance of the microwave phase shifter based on the epitaxial ${\mathrm{Ba}}_{\mathrm{0.6}}{\mathrm{Sr}}_{\mathrm{0.4}}{\mathrm{TiO}}_{\mathrm{3}}$ thin films on (001) MgO is close to that needed for practical applications in wireless communications.