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.