On‐axis dc magnetron sputtering of large area high quality YBa2Cu3O7 superconducting thin films

It is demonstrated by our experiment that using the in situ dc magnetron sputtering method, it is possible to prepare high quality YBa2Cu3O7 (YBCO) thin films with substrates facing the region of plasma ring. The effect of oxygen resputtering can be greatly reduced with a high argon‐oxygen working gas ratio and a large target to substrate distance. It is shown that high quality YBCO thin films of more than 60 mm in diameter, that is about the same size of the diameter of the YBCO target, can be prepared with this process. The thin films were characterized by x‐ray diffractometry, and the critical temperatures were determined by both resistive and ac susceptibility techniques.