Rutherford backscattering analysis of Bi-based superconducting films

Abstract

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 films were deposited on MgO single-crystalline substrates with an aerosol atomized ultrasonically from an aqueous nitrate solution. Precursor films, approximately 5–5.5 μm thick, were then annealed in air at temperatures ranging from 835 to 855°C for 10 h. X-Ray diffraction studies revealed mainly the presence of the 2212 phase (for the bulk, T c is approx. 85 K). Films annealed at temperatures T a≥850°C were superconducting, with T c in the range 60–71 K showing a double T c onset at 85 K and 110 K. The RBS study of the Bi depth profile of precursors showed a maximum content of Bi at a depth of approximately 1–2 μm from the film surface. After film annealing, the Bi content was found to be constant from the surface to approximately 1 μm depth, then decreasing in value towards the film–substrate interface.