Epitaxial growth of superconducting YBa2Cu3O7−x on Si(100) with CaF2 as intermediate buffer

Epitaxial superconducting YBa2Cu3O7−x (YBCO) thin films have been grown on Si(100) using CaF2 as an intermediate buffer layer. The CaF2(100) layers were grown by molecular beam epitaxy while for the YBCO layers a laser ablation process was used. Electron channeling patterns of the YBCO surface show the characteristic four-fold symmetry for c-axis orientation. The epitaxial relationship is (001)YBCO//(001)Si and [010]YBCO//[110]Si. This corresponds to a lattice mismatch of only 1% in the a-b-YBCO interface plane. The 60-nm-thick layers are crack free. Magnetic shielding properties of the epitaxial YBCO layers have been studied by measuring the zero temperature penetration depth λab(0) and the power law dependence of the transition temperature versus magnetic field.