Abstract
Epitaxial YBa/sub 2/Cu/sub 3/O/sub 7-x/ films were grown in situ by reactive coevaporation using a triple-hearth electron-beam gun system, in which a single electron beam is scanned over constituent metal sources. Superconducting properties were improved by using reactive oxygen species generated from an RF discharge during growth and cooling. Zero-resistance temperatures T/sub c/(R=0) of 86-91 K and critical current densities of around 10/sup 6/ A/cm/sup 2/ at 77 K were obtained over the entire MgO