Microstructure of Epitaxial YbBa sub 2 Cu sub 30 sub 7 Superconduction Films Grown by a New Liquid- Gas-Solidification Technique.

We have studied the microstructure of epitaxial YbBa sub 2 Cu sub 30 sub 7 superconducting films grown on SrTiO sub 3 [100] and [110] substrates by a new liquid-gas-solidification processing technique. Films grown on SrTiO sub 3 [100] and [110] substrates are epitaxially oriented with [001] and [110] axes normal to the film surface. Twinned domains of ~200angstroms in size are observed in the [001] oriented films. Most defects observed can be attributed to the presence of stacking faults along the c-axis. The presence of Cu-O bilayer defects is also observed. Rapid oxygen diffusion in the liquid phase is found to play an important role in the microstructure of the thin films.