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

Abstract

High quality epitaxial YBa₂Cu₃O_7−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 T_c (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.