Effect of Overcoating with Dielectric Films on the Superconductive Properties of the High-Tc Y-Ba-Cu-O Films

The high-T c Y-Ba-Cu-O superconductive thin films were coated with dielectric films of Nb2O5 and Al2O3 using an rf-magnetron sputtering technique. The coating with dielectric films lowered the zero-resistance temperature of the Y-Ba-Cu-O films. The Auger analyses for these overcoated Y-Ba-Cu-O films suggested that internal diffusion appeared between the Y-Ba-Cu-O films and the dielectric films. It was also found that the crystallinity of the Y-Ba-Cu-O films was degraded due to the overcoating of the dielectric films.