CHARACTERIZATION OF SPUTTER-DEPOSITED YBACUO FILMS BY X-RAY PHOTOELECTRON-SPECTROSCOPY

Thin films of YBaCuO have been deposited onto SrTiO3 (100) single crystals by different sputter techniques. At substrate temperatures around 700-degrees-C critical current densities as high as 5.9 x 10(6) A/cm2 at 77 K could be achieved. X-ray photoelectron spectroscopy (XPS) has been used to characterize the surface composition and the surface homogeneity of the films. The existence of the superconducting perovskite structure beside other surface species can be detected for example by observing the Ba 4d5/2 emission at its characteristic binding energy of 87.3 eV. Using XPS as a quantitative analytical technique it has been shown that it is possible to detect metallic contamination (Pt, Cr) in the films at a detection limit of 0.1 atomic percent of the cations. The occurrence of the metallic contamination has been traced back to formation of volatile metal-oxides of the substrate heater wires during the deposition process.