QUANTITATIVE XPS ANALYSIS OF HIGH-T(C)-SUPERCONDUCTOR SURFACES

The procedure of quantitative XPS analysis involving the relative sens itivity factors is most convenient to apply to high T(c) superconducto r surfaces because this procedure does not require standards. However, a considerable limitation of such an approach is its relatively low a ccuracy. In the present work, a proposition is made to use for this pu rpose a modification of the relative sensitivity factor approach accou nting for the matrix and the instrumental effects. The accuracy of thi s modification when applied to the binary metal alloys is 2% or better . A quantitative XPS analysis was made for surfaces of the compounds B i2Sr2CuO6, Bi2Sr2CaCu2O8, and YBa2Cu3OY. The surface composition deter mined for the polycrystalline samples corresponds reasonably well to t he bulk stoichiometry. Slight deficiency of oxygen was found for the B i-based compounds. The surface exposed on cleavage of the Bi2Sr2CaCu2O 8 single crystal was found to be enriched with bismuth, which indicate s that the cleavage occurs along the BiO planes. This result is in agr eement with the STM studies published in the literature.