Production of thick YBa2Cu3O7-δ films on sapphire with a cerium oxide sublayer

The feasibility of producing high-quality films of the high-temperature superconducting material YBa2Cu3O7-δ with thicknesses up to 2.6 µm by dc magnetron sputtering is demonstrated. It is found that inclusions consisting of CuO and YBa2Cu3O8 coexist with the growing film and are “sinks” for defects, nonstoichiometric atoms, and mechanical stresses. X-ray diffraction and Rutherford backscattering studies show that the structural perfection of the films increases as the thickness is increased in the proposed production regime.