Effects of Ar Ion-Beam Etching on Gd-Ba-Cu-O Superconducting Thin Films

The effects of Ar ion-beam etching were investigated for Gd-Ba-Cu-O superconducting thin films prepared on (100) MgO substrates at 650°C by rf magnetron sputtering. Etching at acceleration voltages below 2 kV did not change the zero-resistivity temperature and the critical current at 50 K in spite of a reduction of film thickness. A nonsuperconducting layer was formed near the surface. Surface analyses by X-ray photoelectron spectroscopy suggest that the crystal structure was deformed and the mean value of a Cu valence reduced to +1 by the Ar ion bombardment.