XPS STUDY OF NBN AND (NBTI)N SUPERCONDUCTING COATINGS

The chemical composition of the various compounds present in the surfa ce region of NbN and (NbTi)N coatings is studied by X-ray photoelectro n spectroscopy. The high in-depth resolution of this technique enables one to investigate the spacial distribution of various phases within the surface layer, by varying the take-off angle of photoelectrons. Nb 2O5 oxide covers the surface of the NbN coating, while an intermediate oxynitride compound is localized between Nb2O5 and NbN bulk. TiO2 bon ds are present in the outer part of the surface layer of (NbTi)N coati ngs. The unique intermediate oxynitride phase which is present on NbN is split into two different oxynitride energies on (NbTi)N. In both co atings, oxynitride bonds are not found throughout the bulk, although i t contains 0.7% oxygen atoms as impurity.