Preparation of superconducting Y-Ba-Cu-O thin films by rf magnetron sputtering

Superconducting YBa2Cu3O7-x thin films on ZrO2(100), SrTiO3(100), Al2O3 single-crystal substrates have been prepared by rf magnetron sputtering. The targets were Y-Ba-Cu-O compounds made by the solid-state reaction, which are 60 mm × 5 mm in size. Comparing different compositions of targets, we found the YBa3Cu4.5Ox compositions optimal. We prepared the superconducting films under the gases mixed by argon and oxygen (1:1), using about 60 W power with a target-substrate spacing of about 35 mm. The substrate temperature was more than 680 K and the thicknesses of thin films were between 0.4 and 1 μm. After an annealing treatment, we obtained the typical film having a smooth surface that appeared grey-black color, which showed its superconducting transition with an onset temperature at 99 K and zero resistance temperature at 87 K. Some applications about the superconducting thin films will be discussed in this paper.