Mg-doped Ba0.6Sr0.4TiO3 thin films for tunable microwave applications

We report on the microstructural and electrical properties of Mg-doped Ba0. 6Sr0.4TiO3 thin films prepared by the metalorganic solution deposition tech nique using carboxylate-alkoxide precursors at a postdeposition annealing t emperature of 750 degrees C. The structure and morphology of the films were analyzed by x-ray diffraction and atomic force microscopy studies. The ele ctrical measurements were conducted on metal-ferroelectric-metal capacitors using Pt as the top and bottom electrode. The typical measured small signa l dielectric constant and dissipation factor of undoped Ba0.6Sr0.4TiO3 thin films at a frequency of 100 kHz were 450 and 0.013, respectively. The undo ped Ba0.6Sr0.4TiO3 thin films exhibited a high tunability of 28.1% and resi stivity of 0.4 x 10(12) Ohm cm at an applied electric field of 200 kV/cm. T he Mg-doped Ba0.6Sr0.4TiO3 thin films exhibited significantly improved diel ectric loss and insulating characteristics compared to undoped Ba0.6Sr0.4Ti O3 thin films. The effects of Mg doping on the microstructural, dielectric, and insulating properties of Ba0.6Sr0.4TiO3 thin films were analyzed. The high dielectric constant, low dielectric loss, high tunability, and low lea kage current show the potential of pure and Mg-doped Ba0.6Sr0.4TiO3 thin fi lms for integrated capacitor and microwave communication devices. (C) 2000 American Institute of Physics. [S0003-6951(00)02628-0].