PREPARATION OF YBA2CU3O7-Y FILMS BY METAL-ORGANIC CHEMICAL-VAPOR-DEPOSITION USING LIQUID-STATE NONFLUORINATED SOURCES

We have prepared superconducting films by the metal organic chemical v apour deposition (MOCVD) technique using liquid-state fluorinated sour ces and observed the temperature dependence of the morphology of the f ilms. To prevent several problems caused by the existence of fluorine, we prepared YBa2Cu3O7-y (YBCO) films on (100) MgO and (100) SrTiO3 (S TO) substrates by MOCVD using liquid-state nonfluorinated sources in t his work. The reproducibility of the film composition was almost the s ame as for the liquid-state fluorinated sources, and better than in th e case of the solid-state sources. The critical temperature (T-c0) of the film on STO was 89.5 K. A diffusion layer was found between the (1 00) MgO substrate and the YBCO film from measurements by Rutherford ba ckscattering spectroscopy on the film deposited using the fluorinated sources, whereas such a layer did not appear in the films deposited us ing the nonfluorinated sources. This revealed that the films prepared from the nonfluorinated sources had higher quality than the films prep ared from the fluorinated sources.