Abstract:

Superconducting Gd-Ba-Cu-O films with varying Tc were studied by using XPS quantitative analysis, XPS angular distribution, XPS imaging and ion etching. The results show that the surface layer of all films is Ba enriched and lacking in Gd. The elemental distribution on surface is inhomogeneous. The surface and the deep region of the films are contaminated by C-containing compounds. As compared with the sample with Tc≥87K, the sample with Tc＜77K has the highest atomic concentration of Ba(HBE) and O(HBE) corresponding to non-superconducting phase on the surface. In the deep region (20-30 nm) of sample with Tc＜77K, the chemical composition is still nonstoichiometry. The contamination of C-containing compounds in both the surface and the deep region is more serious for the sample with Tc＜77K than the samples with Tc≥87K.

Key words: Superconducting Gd-Ba-Cu-O films, XPS, XPS imaging, Ar+ ion etching