Preparation of YBa2Cu3O7-y films by metal organic chemical vapour deposition using liquid-state nonfluorinated sources

We have prepared superconducting films by the metal organic chemical vapour deposition (MOCVD) technique using liquid-state fluorinated sources and observed the temperature dependence of the morphology of the films. To prevent several problems caused by the existence of fluorine, we prepared YBa2Cu3O7-y (YBCO) films on (100) MgO and (100) SrTiO3 (STO) substrates by MOCVD using liquid-state nonfluorinated sources in this work. The reproducibility of the film composition was almost the same as for the liquid-state fluorinated sources, and better than in the 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 (100) MgO substrate and the YBCO film from measurements by Rutherford backscattering spectroscopy on the film deposited using the fluorinated sources, whereas such a layer did not appear in the films deposited using the nonfluorinated sources. This revealed that the films prepared from the nonfluorinated sources had higher quality than the films prepared from the fluorinated sources.