THE SPUTTER-DEPOSITION OF CERIUM OXIDE THIN-FILMS FOR SUPERCONDUCTIONELECTRONICS

Thin films of cerium oxide (CeO2) have been deposited by r.f. reactive sputter deposition on yttria-stabilised zirconia (YSZ) and on YBCO th in films on lanthanum aluminate (LaAlO3) substrates. Subsequent growth of YBa2Cu3O(7-x) (YBCO) by high pressure d.c. sputtering has yielded superconducting transition temperatures (T-c's) of 89-91 K for unpatte rned YBCO films. CeO2 thin films have been patterned and subsequent YB CO growth has been examined. Oxygenation levels were monitored between growth and patterning stages by X-ray diffraction (XRD).A YBCO track has been fabricated crossing steps in a CeO2 buffer layer. A critical current density (J(c)) of 0.8 x 10 Am-10(-2) at 77 K as compared with 1 x 10 (10) Am-2 for a flat YBCO track on flat CeO2 was measured. Cros sover test structures were made, having T,'s of 89-91K for top and 80- 90K for the bottom YBCO electrodes. A 400 nm thickness of CeO2 was suf ficient to insulate two superconducting layers and found to have a res istivity of 2x10(7) Omega m at 77K.