SRXBA(1-X)TIO3 THIN-FILMS FOR ACTIVE MICROWAVE DEVICE APPLICATIONS

Thin (0.3 - 50 mu m) films of SrxBa(1-x)TiO3 (SBT) with x=0.35 - 0.8 h ave been deposited by pulsed laser deposition onto single crystals of MgO, LaAlO3 and thin films of YBa2Cu3O7-delta The SBT films were chara cterized morphologically, structurally and electrically at frequencies less than or equal to 13 GHz. On MgO, smooth, oriented single phase f ilms were obtained at substrate temperatures greater than or equal to 825 degrees C. Films as thick as 10 mu m were exclusively (100) orient ed. At thicknesses approaching 50 mu m SBT films were phase pure but p olycrystalline. The dielectric constant of SBT films, as determined fr om patterned structures using microstrip geometries, was similar to 20 % of that observed in bulk SET (epsilon(max)(film)=1100 for x=0.5 at 2 00 K). The temperature dependence of the dielectric constant was broad in comparison to the sharply peaked behavior of the bulk material. Th e ferroelectric thin film properties described, while significantly di fferent from bulk material, are very encouraging for use in active dev ices at microwave frequencies.