Preparation and Processing of Thin Film Ba sub 2 YCu sub 3 O sub 7.

While many important milestones have been reached in the technological development of high-temperature superconductivity, the field is still in its infancy, and optimal routes for preparation and processing have not necessarily been identified. We have examined various alternatives appropriate for thin film applications. Films of Ba sub 2 YCu sub 3 O sub 7 have been prepared by two novel techniques. The first employs vacuum coevaporation of Y, Cu and BaF sub 2 in an oxygen ambient. The use of BaF sub 2 rather than metallic Ba is found to give superior results, including routine values for T sub c sup (R=0) of 89-92K in films 200-700 nm thick, ease of pattern definition by liftoff or wet-etch processing, and critical current densities as high as 1x10 sup 6 A-cm sup (-2) at 82K in a film 200 nm thick.