J. Phys. IV France 02 (1991) C2-287-C2-294
THERMODYNAMIC MODELING OF MOCVD OF THE SUPERCONDUCTING PHASE IN THE Bi-Sr-Ca-Cu-O SYSTEM : INFLUENCE OF METAL PRECURSOR AND OXYGEN SOURCEA. HÅRSTA and J.-O. CARLSSON
Thin Film and Surface Chemistry Group, Department of Inorganic Chemistry, University of Uppsala, Box 531, S-751 21 Uppsala, Sweden
Chemical vapour deposition (CVD) of the superconducting 2:2:1:2 phase in the Bi-Sr-Ca-Cu-O system from different metalorganic precursors is thermodynamically investigated. Both precursors without fluorine and fluorine-containing precursors were employed. The oxygen source was O2, H2O, O2+H2O or N2O. The effect of different deposition parameters on the extension of the region where the 2:2:1:2 phase can be deposited is studied, and the results are presented in calculated CVD stability diagrams. For precursors containing no fluorine, the best conditions were obtained by using N2O as the oxygen source and by using a low total pressure. For fluorine-containing precursors, the best conditions were obtained using a mixture of O2 and H2O as the oxygen source. Moreover, the size of the region where the2:2:1:2 phase can be deposited is reduced compared to when precursors without fluorine are used. The results of the thermodynamic calculations are found to agree well with experimental results.
© EDP Sciences 1991