Preparation and characterization of high Tc YBa2Cu3O7−x thin films on silicon by dc magnetron sputtering from a stoichiometric oxide target

The effects of deposition temperature and O2 pressure during cool down on the superconducting properties of YBa2Cu3O7−x thin films on Si substrates by DC magnetron sputtering from a stoichiometric oxide target are reported. Results from X‐ray diffraction analysis indicate that the films deposited at 400 °C or lower, at 650 °C and cooled down in ≳10−4 O2, and at 650 °C and cooled down in ≳0.16 Torr O2 have, respectively, amorphous, tetragonal, and orthorhombic structure. Superconducting orthorhombic films with a zero resistance Tc of as high as 76 K have been thus prepared on Si directly, without further heat treatments. The deposition of these films on Si is possible because of the minimal film‐substrate interaction at the relatively low deposition temperature used, as indicated by the depth profiles obtained for these films using secondary ion mass spectrometry. Results of cross‐sectional transmission electron microscopic studies of some of these films with different Tc and X‐ray photoemission spectrosco...