Reaction patterning of YBa2Cu3O7−δ thin films on Si

A novel technique exploiting the severe chemical reaction between Si and YBa2Cu3O7−δ (YBCO) has been developed for patterning epitaxial YBCO films in situ. Patterning is achieved by etching features in epitaxial YSZ on Si(100), and then depositing a final layer of YBCO; the material which grows on the exposed Si is insulating. Linewidths down to 3 μm have been demonstrated with a zero resistance critical temperature (Tc) of 86 K and a transport critical current density of 1.6×106 A/cm2 at 77 K. 45° and low-angle twist grain boundaries occur under some circumstances but can be eliminated by regrowing 20 Å of homoepitaxial YSZ on the surface prior to YBCO growth. Si diffusion in insulating portions has been characterized by x-ray photoemission spectroscopy, indicating vertical diffusion through the film.