The microstructure and crystallinity of epitaxial YB2Cu3O7-delta, (YBCO) thin films grown on a silicon using a buffer of Eu2CuO4 (ECO)/Yttrium-stabilized Z(r)O(2) (YSZ) were investigated by X-ray high-resolution diffraction, small angle reflection, and reciprocal space map, as well as atomic force microscopy. The results showed that YBCO films with a buffer of ECO/YSZ were well oriented in the [00L] direction perpendicular to the substrate surface. The rocking measurements for the YBCO films grown on ECO/YSZ buffered Si show a smaller value of the full widths at half maximum (similar to 2.07 degrees) in comparing with that of the YBCO with a single YSZ buffer (similar to 4.48 degrees). Moreover, the surface morphology of YBCO films with an ECO/YSZ buffer is significantly improved. The average size of gains on the surface was much smaller, indicating that growth of YBCO on Si with such a buffer of ECO/YSZ is highly epitaxial. (c) 2005 Elsevier B.V. All rights reserved.