FORMATION OF ORIENTED HIGH-TC SUPERCONDUCTING BI-SR-CA-CU-O THIN-FILMS ON SILVER SUBSTRATES BY ORGANOMETALLIC CHEMICAL VAPOR-DEPOSITION

Highly oriented thin films of the high Tc Bi-Sr-Ca-Cu-O superconductor have been deposited on silver substrates by low-pressure organometallic chemical vapor deposition. The volatile metalorganic complexes Cu(acetylacetonate)2, Sr(dipivaloylmethanate)2, Ca(dipivaloylmethanate)2, and triphenyl bismuth are used as precursors with N2O as a reactant gas. X-ray diffraction measurements reveal that the films deposited at 625°C contain a mixture of the Bi 2(Sr,Ca)2CuOx and Bi2(Sr,Ca) 3Cu2Ox phases. The post-annealed films are predominantly composed of the Bi2(Sr,Ca)3Cu 2Ox phase with preferential orientation of the crystallite c axes perpendicular to the substrate surface. Magnetic susceptibility measurements indicate the superconducting onset temperature of the annealed films to be at 80 K. The zero-field critical current density, estimated from magnetization measurements, is ∼3.9×105 A/cm2 at 5.5 K.