THERMODYNAMIC MODELING OF MOCVD OF THE SUPERCONDUCTING PHASE IN THE Bi-Sr-Ca-Cu-O SYSTEM: INFLUENCE OF METAL PRECURSOR AND OXYGEN SOURCE

Chemical vapour deposition (CVD) of the superconducting 2:2:1:2 phase in the Bi-Sr-Ca-Cu-0 system from different metalorganic precursors is thermodynamically investigated. Both precursors without fluorine and fluorine-containing precursors were employed. The oxygen source was O, H,O, O,+H,O or N,O. 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 N, O as the oxygen source and by using a low total pressure. For fluorine-containing precursors, the best conditions were obtained using a mixture of 0, and H, O as the oxygen source. Moreover, the size ofthe 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.