Local stoichiometry measurement of Y-Ba-Cu-O thin layers grown by metal organic chemical vapor deposition

Y-Ba-Cu-O thin films with different stoichiometry were grown by metal organic chemical vapor deposition on MgO and SrTiO3. The samples showed superconducting behavior in a wide range of average stoichiometry. However, energy dispersive x-ray spectroscopy (EDX) measurements show that best results can be obtained only in a small stoichiometry range. Critical temperatures of Tc≳89 K and critical current densities of jc (77 K)≳2×106 A/cm2 could be obtained with optimized stoichiometry. Spatially resolved EDX measurements show that copper tends to form precipitates on the layers if its average content exceeds 50 mol %, while yttrium is incorporated into the matrix if offered in excess.