A Reproducible Technique for Fabrication of Thin Films of High T sub c Superconductors.

We report on a new process to make films of Y sub 1 Ba sub 2 Cu sub 3 O sub 7 using coevaporation of Y, Cu, and BaF sub 2 on SrTiO sub 3 substrates. The films have high transition temperatures (up to 91 K for a full resistive transition), high critical current densities (10 sup 6 A/cm sup 2 at 81 K), and a reduced sensitivity to fabrication and environmental conditions. Because of the lower reactivity of the films, we have been able to pattern them in both the pre-annealed and post-annealed states using conventional positive photoresist technology.