Preparation of YBa2Cu3O7−δ thin films by magnetron sputtering with i n s i t u plasma oxidation

Superconducting YBa2Cu3O7−δ thin films with surface roughness Ra∼20 Å have been successfully prepared by either rf or dc magnetron sputtering. The substrate temperature was kept at 600–670 °C during deposition and a subsequent in situ plasma oxidation treatment was performed at 480–520 °C. The films deposited on single-crystal SrTiO3 (100) exhibited zero resistance at 91 K and had the critical current density of 3×106 A/cm2. In this paper we describe the influences of fabrication conditions on film superconductivity.