Y-Ba-Cu-O superconducting films produced by long-pulse laser vaporization

Deposition of superconducting thin films from YBa2Cu3O7 targets using a long-pulse (ms) Nd-glass laser with 50 J/pulse energy has been demonstrated. The deposition rate was approximately 100 nm/pulse and the film stoichiometry was close to that of the target. Scanning electron microscopy revealed spherical inclusions in the film. Scanning tunneling microscopy in air showed a terrace-ledge structure on the uniform portion of the film. A film produced by four pulses on a SrTiO3 substrate, held at 540 °C, and post-annealed in O2 at 850 °C for about 2h exhibited an onset transition at 78 K and zero resistance at 61 K. This new approach can provide fast deposition rates and broad-area film coverage per laser shot.