YBA2CU3OX EPITAXIAL-FILMS PREPARED BY RF MAGNETRON SPUTTERING - DEPOSITION MECHANISMS, STRUCTURE AND SUPERCONDUCTING PROPERTIES

YBa2Cu3O(x) epitaxial films on (100) MgO crystal splits have been prepared by off-axis RF magnetron sputtering. Two deposition mechanisms of epitaxial film growth, atomic and molecular, have been observed at different deposition pressures. YBa2Cu3O(x) films have T(c0) = 81-85 K, DELTA-T(c) = 3-5 K and c-axis lattice parameter c = 11.70-11.82 angstrom, depending on deposition conditions. Possible reasons for c-axis expansion have been considered. Expansion of the c-axis lattice parameter at low deposition pressure is explained by crystal defects due to inhomogeneous oxygen distribution in the YBa2Cu3O(x) crystal structure. Epitaxial films with perfect structure and the best superconducting properties grow under molecular mechanism conditions and the absence of significant high energy particle bombardment.