Bi-Sr-Ca-Cu-O film on sapphire grown by plasma-enhanced halide CVD

Plasma-enhanced halide chemical vapor deposition (CVD) for Bi-Sr-Ca-Cu-O (BSCCO) thin film has been developed. Superconducting BSCCO films were fabricated on 3-in-diameter sapphire substrates without postannealing. The CVD apparatus has four source-gas generation cells in which source materials (BiCl/sub 3/, SrI/sub 2/, CaI/sub 2/, and CuI) are evaporated or sublimated by heaters. Source gases are carried to the deposition chamber with helium. Oxidizing gases are O/sub 2/ and/or H/sub 2/O. The total pressure in the deposition chamber was 0.1 torr, and the O/sub 2/ partial pressure was 0.01 torr. Deposition was at 2 AA/min. It was found that the superconducting BSCCO film could be deposited on sapphire substrates at less than 700 degrees C without a solid-phase reaction between the film and substrate and that plasma-enhanced CVD controlled the BSCCO phases even at 580 degrees C. RF-plasma enhancement resulted in as-deposited superconducting BSCCO films. The c-axis orientation of the films was perpendicular to the sapphire's (1102)-plane. The 700-AA-thick (2212)-phase BSCCO film showed that the resistive transition started at about 100 K and that the zero-resistivity temperature was 70 K. The critical current density was about 2.5*10/sup 6/ A/cm/sup 2/ at 10 K.