Superconducting characteristics and epitaxial-growth analyses of YBa₂Cu₃O_7−x thin films by direct-current magnetron sputtering

Abstract

Using direct-current magnetron sputtering deposition, we have successfully prepared highquality epitaxial YBa₂Cu₃O_7−x thin films, on (1 0 0) and (1 1 0) ZrO₂, SrTiO₃ and LaAlO₃ substrates. The films reached zero resistance at about 90 K and had a critical current density, J _c (at 77 K, H=O), above 10⁶ Acm⁻². Electrical measurements showed that the films had a small microwave surface resistance. The epitaxial structure of the films was studied by X-ray diffraction (XRD), Rutherford backscattering (RBS) and channeling spectroscopy, X-ray double-crystalline diffraction and transmission electron microscopy (TEM). It was found that the c-axis of the film grown on the (1 0 0) substrates under optimum deposition conditions was perpendicular to the substrate surface. But on the (1 1 0) substrates, epitaxial growth was along the (1 1 0) or (1 0 3) direction. The experimental results indicate that the films had excellent superconducting properties and complete epitaxial structure.