Formation of thin film YBaCuO Superconductors from Cu/BaO/Y2O3 Layer Structures

Thin film superconductors of the YBaCuO family have been fabricated using layer structures of Cu/BaO/Y2O3 deposited by electron-beam evaporation. Using layer thicknesses off the stoichiometric YBa2Cu3O7, we have formed superconducting films with zero resistance above 77°K using MgO and SrTiO3 substrates. The films were found to be composed of both the superconducting YBa2Cu3O7 phase, and the non-superconducting green Y2BaCuO7 phase. Dependence of transition temperatures on the annealing temperatures and the substrates has also been studied.