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

Dielectric Ba0.6Sr0.4TiO3 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 250 degrees at 23.675 GHz under an electrical field of 40 V/mum and a figure of merit of similar to 53 degrees /dB. The performance of the microwave phase shifter based on the epitaxial Ba0.6Sr0.4TiO3 thin films on (001) MgO is close to that needed for practical applications in wireless communications. (C) 2001 American Institute of Physics.