Fabrication of YBa₂Cu₃O₇ Superconducting Nanocomposite Film on Silicon Substrate

Abstract

Fabrication of YBa 2 Cu 3 O 7 nanocomposite films on silicon substrates is required for superconducting electromagnetic devices. Low-temperature deposition is effective in suppressing the chemical reaction between YBa 2 Cu 3 O 7 and Si, while sufficient diffusion is required to form the well-defined nanocomposite structure. The fabrication of the YBa 2 Cu 3 O 7 nanocomposite films on Si substrates should simultaneously satisfy these conflicting requirements. A YSZ (yttrium stabilized zirconia) buffer layer was epitaxially grown on Si substrates to suppress the chemical reaction. Then, the YBa 2 Cu 3 O 7 + Ba 2 YbNbO 6 films were fabricated on the YSZ/Si. The nanorods with diameters of 9−17 nm were elongated along the c-axis even at the low deposition temperature. The YBa 2 Cu 3 O 7 + Ba 2 YbNbO 6 nanocomposite film exhibited a critical temperature of 86.0 K, which is comparable to the critical temperature of 85.6 K in the pure film. The irreversibility temperature was slightly improved by the nanorods. Thus, we demonstrate the formation of nanorods in the YBa 2 Cu 3 O 7 films on Si substrates without lowering the critical temperature. This opens the superconducting electromagnetic devices integrated with high-temperature superconductors and semiconductors.