FORMATION OF Y1BA2CU3O7-X THIN-FILMS BY PULSED RUBY-LASER ABLATION

Thin films of the superconductor Y1Ba2Cu3O7-x have been grown on MgO ( 100) substrates by pulsed ruby laser ablation. The heatflow in the Y1B a2Cu3O7-x target irradiated with the pulsed ruby laser was simulated. The laser energies required for the onset of melting and vaporization were determined, and compared with experimentally determined values. R utherford backscattering spectrometry was used to measure the thicknes s and stoichiometry of the deposited layers, while x-ray diffraction w as employed to extract phase and orientational information. It was fou nd that the ruby laser can deposit superconducting material with near ideal stoichiometry. The spatial distribution of the deposited films d isplays a CoS(n)(theta) dependence (8 < n < 12) which is consistent wi th the high degree of forward peaking usually found in pulsed laser de position. The amount of material deposited in an oxygen ambient of 10( -1) mbar with an incident energy density of 2 J cm-2 was between 1.0 a nd 1.5 nm per pulse for a target-substrate separation of 15 mm. Resist ivity measurements of films deposited at 200-degrees-C and post anneal ed at 850-degrees-C revealed a T(c) (onset) of 84 K and a transition w idth DELTAT of 2 K. Susceptibility measurements gave a depressed tempe rature of 80 K and a broader transition width of 7.5 K pointing to wea k intergranular links.