THIN-FILM MULTILAYER CONDUCTOR FERROELECTRIC TUNABLE MICROWAVE COMPONENTS FOR COMMUNICATION APPLICATIONS

A study of Au/SrTiO3/YBa2Cu3O7-delta/LaAlO3 and (Au,YBa2Cu3O7-delta)/B axSr1-xTiO3/LaAlO3 (x = 0, 0.50, and 0.40) multilayered structures is presented. At 1.0 MHz, the largest tuning of Au/SrTiO3/YBa(2)Cu(3)0(7- delta) parallel plate capacitors corresponded to single-phased, epitax ial 300-500 nm thick SrTiO3 thin films deposited at 800 degrees C. For SrTiO3/LaAlO3 structures having SrTiO3 films of similar quality, we o bserved that at 1.0 MHz and 77 K, interdigital capacitors exhibit high er tunabilities and lower losses than parallel plate configurations, b ut required higher dc voltage. For a 300 nm thick SrTiO3 film, a 25 Om ega YBa2Cu3O7-delta/SrTiO3/LaAlO3 phase shifter exhibited a phase shif t similar to 2.6 times larger than its Au/SrTiO3/LaAlO3 counterpart. A t 19 GHz and 32V, a 360 degrees phase shift could in principle be achi eved with coupled microstripline sections only 7.0 mm long. At 14 GHz, 77 K and 260 V, for 1.0 mu m and 300 nm thick SrTiO3 films, 25 Omega 360 degrees Au/SrTiO3/LaAlO3 phase shifters would be nominally 4.0 mm and 12 mm long, respectively. For a 2 lambda YBa2Cu3 O7-deltaSrTiO3/La AlO3 ring resonator a tuning rate of 0.7 MHz/Volt was achieved at 10 G Hz and 77 K. The relevance of these structures for phased array antenn as and as tunable elements in discriminator-stabilized oscillators is discussed.