INSITU GROWTH OF Y-BA-CU-O FILMS BY LASER DEPOSITION

Superconducting thin films of Y-Ba-Cu-O have been prepared in-situ on SrTiO3 and MgO, ? 100 ? oriented, substrates by UV laser ablation of a massive sintered pellet. The deposition process is studied as a function of the laser fluence and the oxygen partial pressure using a fixed substrate thermal cycle. The sample-holder is a small oven where the sample is free-standing and a good temperature homogeneity can be obtained. For laser fluences between 1.5 J/cm2 and 2.5 J/cm2, and O2 partial pressures above 10 Pa consistently high-quality c-axis epitaxial YBa2Cu3O7 films are obtained. The superconducting transitions in these films depend strongly on the overall oxygen content and there is structural evidence for oxygen phase-segregation in those which are oxygen deficient.