LASER-SURFACE INTERACTION DURING AND AFTER DEPOSITION OF THIN OXIDE-FILMS

Thin films of PZT (Pb(Zr0.54Ti0.46)O-3) were deposited by KrF and XeCl excimer laser ablation onto platinated silicon wafers (Si/Pt) and ytt rium stabilized zirconia (YSZ) covered with YBa2Cu3O7-x (YSZ/YBCO). Th e substrate temperature (T-s) ranged from 240 to 720 degrees C and the substrate surface was optionally activated by excimer laser irradiati on (ArF, KrF) during deposition. On Si/Pt substrates PZT showed permit tivity values of epsilon less than or equal to 200 only, with ArF lase r activation (20 mJ/cm(2), T-s = 360 degrees C) epsilon = 360. On YSZ/ YBCO samples, ferroelectric PZT of dominantly perovskite crystal struc ture was obtained at T-s = 500-700 degrees C with epsilon less than or equal to 750. With surface activation (ArF: less than or equal to 35 mJ/cm(2), KrF: less than or equal to 85 mJ/cm(2)) at T-s = 350-500 deg rees C PZT showed epsilon = 500-1200. In dc SQUIDs one Josephson junct ion was selectively heated above T-c by Ar+ laser irradiation to measu re the critical current of the second junction individually. At high A r+ laser intensity O-2 effusion from YBCO was used to narrow the junct ion width in steps of 1 mu m. The width reduction from 23 to 9 mu m in both junctions resulted in a flat baseline of the SQUID and an increa se of the voltage modulation amplitude from 8 to 12 mu V. Passivation layers for YBCO consisting of AuOx, PtOx, and AuAgOx showed O-2 effusi on upon Ar+ laser irradiation depending on the laser intensity, The el ectrical contact resistance decreased from 10(-2) Omega cm(2) to 5 x 1 0(-7) Omega cm(2) when converting AuAgOx to AuAg. The superconductivit y in YBCO under the laser modified contact was completely preserved.