Epitaxial thin films of YBa2Cu3O7−x on LaAlO3 substrates deposited by plasma-enhanced metalorganic chemical vapor deposition

High quality epitaxial YBa2Cu3O7−x (YBCO) superconducting thin films (0.3 μm thick) were grown on the closely lattice and thermal expansion matched substrate, LaAlO3, which has low dielectric loss. The YBCO layers were prepared, in situ, by a microwave plasma-enhanced metalorganic chemical vapor deposition process. The films, which had mirror-like smooth surfaces, were deposited at a substrate temperature of 730 °C with a partial pressure of 2 Torr of N2O. The electrical resistance and magnetic susceptibility versus temperature of the as-deposited films show metallic behavior in the normal state and sharp superconducting transitions with Tc (R=0) of 88 K. Critical current densities measured on patterned bridges were 5×105 A/cm2 at 78 K for the films deposited on LaAlO3. X-ray diffraction measurements indicate that films grow epitaxially in the plane of the substrate with axis perpendicular to the substrate surface.