Preparation of YBCO thin film by MOCVD method using new liquid metal organic precursors

New low melting point yttrium, barium, and copper completes were synthesize d for metalorganic chemical vapor deposition (MOCVD), tris(2,3,6,6-tetramet hyl-3-5-octandionato)yttrium (Y(TiMOD)(3)), Ba(TMOD)(2), and bis(6-ethyl-2, 2-dimethyl-3,5-octnnedionato)copper (Cu(EDMOD)(2)). The melting point of Y( TMOD)(3), 95 degrees C, is 80 degrees C lower than that of the conventional tris(dipivaloylmethanato)yttrium (Y(DPM)(3)), The melting point of Cu(EDMO D)(2) is 78 degrees C, which is 120 degrees C lower than that of Cu(DPM)(2) . For fabrication of YBa2Cu3Oy-delta thin films, these completes were used in the liquid state where a stable deposition rate could be obtained; the Y (TMOD)(3) and the Cu(EDMOD)(2) were heated at 105 degrees C and 90 degrees C, respectively, and the mixture of Ba(DPM), and Ba(TMOD), in the ratio of 4 to 1 was used at 215 degrees C. Single crystal STO(100) was used as a sub strate. Substrate temperature was 800 degrees C, The thin films, the thickn ess of 200 nm, were obtained. The XRD patterns of all the samples showed th e preferred orientation of the c-axis normal to the substrate surface. The superconductivity was confirmed at 78 K.