Postgrowth annealing of YBa2Cu3O7−x thin films in an electron cyclotron resonance oxygen plasma

As-deposited epitaxial YBa2Cu3O7−x films have been prepared by laser ablation in molecular oxygen followed by a cooling procedure in an electron cyclotron resonance (ECR) plasma. We demonstrate that cooling in a plasma provides a more homogeneous oxygenation than cooling in a neutral oxygen environment. Alternating-current susceptibility, resistivity, and x-ray diffraction measurements have been used to compare the influence of the cooling in an ECR oxygen plasma and a neutral oxygen environment on the properties of YBa2Cu3O7−x thin films. The role of the atomic oxygen content of the plasma is discussed starting from an optical and electrical diagnosis of the plasma.