INSITU DEPOSITION OF SUPERCONDUCTING BI-PB-SR-CA-CU-O THIN-FILMS ON MGO(100) SUBSTRATES BY RF MAGNETRON SPUTTERING AND LASER ABLATION

Superconducting thin films of Bi-Pb-Sr-Ca-Cu-O (BPSCCO) have been prepared in situ by magnetron sputtering and laser ablation onto heated MgO (100) substrates. Post-deposition annealing at higher temperatures was not required to obtain superconducting BPSCCO films, and a narrow temperature window in a very similar temperature region was observed for the growth of oriented films for both the laser ablation and magnetron sputtering technique. The best films were smooth and shiny with their c axes oriented perpendicular to the substrate surface but scanning electron microscope analysis showed particulates on the film surface. Room-temperature resistivity values of the order of 2-3 mΩ cm were obtained for these films. At 70 K and 8 T, the resistivity ratio for the H⊥ and ∥ to the plane of the film was ∼25 for an applied current density J of 0.8 A/cm2. Rutherford backscattering analysis on the laser-ablated and sputtered films indicates that the BPSCCO films had 2223 composition while the x-ray diffraction studies indicated mixed 2212 and 2223 phases.