Rutherford backscattering analysis of Bi-based superconducting films

The elemental composition, film thickness and concentration depth profiles of precursor and superconducting (Bi, Pb)-Sr-Ca-Cu-O films were studied by the Rutherford backscattering spectrometry (RBS) technique. The precursor f ilms were deposited on MgO single-crystalline substrates with an aerosol at omized ultrasonically from an aqueous nitrate solution. Precursor films, ap proximately 5-5.5 mum thick: were then annealed in air at temperatures rang ing from 835 to 855 degreesC for 10 h. X-Ray diffraction studies revealed m ainly the presence of the 2212 phase (for the bulk, T-c is approx. 85 K). F ilms annealed at temperatures T-a greater than or equal to 850 degreesC wer e superconducting, with T-c in the range 60-71 K showing a double T-c onset at 85 K and 110 K. The RES study of the Pi depth profile of precursors sho wed a maximum content of Bi at a depth of approximately 1-2 mum from the fi lm surface. After film annealing, the Pi content was found to be constant f rom the surface to approximately 1 mum depth, then decreasing in value towa rds the film-substrate interface. (C) 2000 Elsevier Science S.A. All rights reserved.