DOUBLE-SIDED YBA2CU3O7-X THIN-FILMS FOR MICROWAVE APPLICATIONS

YBa2Cu3O7-x (YBCO) thin films with superconducting transition temperat ures above 91 K were deposited on both sides of double-sided, polished LaAlO3(100) substrates. Using ex situ furnace annealing, the substrat es could be kept at 45-degrees-C during the codeposition of Y, Cu and BaF2. No 02 was necessary in the deposition chamber. The furnace annea ling was carried out in a mixture of Ar, O2 and H2O vapour. The gas fl ow was 1000 sccm at an O2 partial pressure of 1.0 mbar. The maximum an nealing temperature was 810-degrees-C which was maintained for 1 h. Do uble-sided YBCo superconducting thin films may provide a good base mat erial for microwave devices in which one superconducting side acts as a low-loss ground plane.