Preparation of Superconducting YBa₂Cu₃O7-x Films by ECR Plasma Sputtering

Y-Ba-Cu-O films were prepared on (100)MgO single crystal substrates by ECR plasma sputtering. As-deposited films without substrate heating were amorphous and electrically insulating. The amorphous film was crystallized to YBa 2 Cu 3 O 7- x by postannealing at 930°C for 1 min in O 2 gas, and the T c of the postannealed film was 70.5 K. The film prepared at the substrate temperature of 650°C was crystalline YBa 2 Cu 3 O 7- x and the T c of the film without any postannealing was 73 K.