Cross sections for O-16(He,He)O-16 resonant elastic scattering and application to elemental analysis of YBa2Cu4O8 and Nd1+xBa2-xCu3O7-delta films grown on SrTiO3

The differential cross sections for O-16(He,He)O-16 resonant elastic scattering at 3.034 and 3.078 MeV have been measured using stoichiometric thin (100 Angstrom) and thick (6000 Angstrom) SiO2 layers formed on Si(100) wafers by thermal oxidation at 900 degrees C under H-2 and O-2 flows. We have determined the resonance widths (Gamma) and interaction radii (a), which are the parameters defining the cross sections in the partial wave analysis, by best fitting the angular and energy dependent scattering yields from oxygen. A computer simulation program for Rutherford backscattering including the O-16(He,He)O-16 resonant scattering has been synthesized and applied to the elemental analysis of thin YBa2Cu4O8 and Nd1+xBa2-xCu3O7-delta films grown on SrTiO3 substrates. The present elemental analysis is compared with the transition temperatures of superconductivity (T-c) in the context of the oxygen deficiency. The accuracy of oxygen content is estimated to be better than 0.1 (a few %). How to improve the accuracies of the elemental analysis, in particular the oxygen content, is dis cussed in detail. (C) 1996 American Institute of Physics.