DC SPUTTERING DEPOSITION OF A-AXIS-ON-C-AXIS DOUBLE-LAYER Y-BA-CU-O FILMS

High quality epitaxial a-oriented (a-axis perpendicular to the substrate) and c-oriented high T(c) superconducting Y-Ba-Cu-O (YBCO) films on SrTiO3 and LaAlO3 have been fabricated by inverted cylindrical magnetron sputtering system. In this study we report the fabrication process and material characterization of a double-layer structure consisting of both a-axis and c-axis YBCO films. Both the transition temperature T(c) and the critical current density J(c) have been degraded but the orientation of each layer of YBCO remains its distinguishing pattern as indicated by X-ray diffraction. Extended defects in the interface have been further confirmed by Rutherford backscattering spectroscopy with channeling. Breaking the vacuum chamber to deposit the films seems to have no major effect on the surface microstructure of the films. The possible applications based on this homojunction will also be discussed.