DEPOSITION BY PLASMA-ASSISTED LASER-ABLATION AND MASKLESS PATTERNING OF YBA2CU3O7-X SUPERCONDUCTING THIN-FILMS

YBa2Cu3O7-x superconducting thin films were deposited in situ by plasm a-assisted laser ablation onto polycrystalline yttria-stabilized-zirco nia (YSZ) substrates at 700-degrees-C in a low pressure (200-400 mTorr ) O2 discharge (-300 V). The laser operated at 5 - 50 Hz repetition ra te and was focused onto a superconducting target with a typical energy density of 2.5 - 4 J cm-2. An in situ annealing step in 1 Torr O2 atm osphere at 425-degrees-C for 1-2 h was followed by slow cooling of the films to room temperature. The YBa2Cu3O7-x films grew preferentially oriented with the c-axis normal to the substrate surface. They exhibit ed metallic behaviour in the normal state and superconducting transiti ons with typical onset of 91 K and zero resistance between 82 and 87 K . The transport critical current densities J(c) were 10(2) A cm-2 for 1 mum thick films and two orders of magnitude higher, J(c) = 3 x 10(4) A cm-2, for 0.08 mum thick films. Maskless patterning was achieved by utilizing the ArF laser beam to induce etching selectivity of the sup erconducting thin films. For this purpose, the central part of the bea m was apertured by a slit and focused onto the sample by means of a 15 x Schwarzschild microscope objective to give an irradiated area on th e sample of approximately 10 x 150 mum2. The laser energy density on t he sample was typically 10(3) J cm-2, while the repetition rate was va ried between 10 and 20 Hz. Microbridges of different geometries with a maximum resolution of 10 mum and high edge definition were obtained a t 20 mum s-1 scan rate using this technique.