Analysis of stoichiometry of high- Tc superconducting films by RBS and PIXE methods

Lateral inhomogeneity has been studied in thin films of YBa ₂Cu ₃O _{7 - δ} deposited from aerosol on MgO substrates. RBS and PIXE analyses distinguished areas that were found to differ in the critical temperature T_c values. The PIXE results confirmed the differences in composition between those areas. Variations in layer thicknesses were found by means of RBS analysis. Measurements made with a microbeam showed that the film within each of those areas was homogeneous. However, significant variations in the YBaCuO stoichiometry and local changes in the film thickness were found in the intermediate zone between areas with T_c = 85 K and T_c = 80 K.