INSITU GROWTH OF EPITAXIAL YBA2CU3O7 THIN-FILMS BY ON-AXIS UNBALANCEDDC MAGNETRON SPUTTERING

In-situ superconducting YBa2Cu3O7 thin films are grown epitaxially ont o MgO(100) substrates by on-axis d.c. magnetron sputtering. The magnet ron uses an unbalanced magnetic field configuration to circumvent resp uttering effects, and high quality thin films are realized with excell ent reproducibility. A stoichiometric target is sputtered in an Ar-O2 mixture (Ar-to-O2 ratio of 15 to 1) and films are deposited onto the h eated substrates placed 40 mm directly in front of the target. We repo rt on the growth and properties of films prepared as a function of spu ttering pressure p(t) = 1 - 100 Pa, and as a function of the heater te mperature T(s) = 600-860-degrees-C. c axis epitaxy is obtained over a wide range of deposition conditions (T(s) greater-than-or-equal-to 700 -degrees-C; p(t) greater-than-or-equal-to 30 Pa). Typical films have e xcellent crystalline quality, a transition temperature T(c) = 85-90 K, a critical current density J(c)77 K greater-than-or-equal-to 10(6) A cm-2 and a resistance ratio R300 K/R100 K = 2.0-3.1.