DYBA2CU3OX SUPERCONDUCTING THIN-FILMS GROWN BY MBE

Superconducting DyBa2Cu3O6.8 (orthorhombic I phase) thin films were grown in situ on NdGaO3 (001) and (110) substrates at 400-440-degrees-C by molecular beam epitaxy (MBE). The c-axis lattice constant and the critical temperature were c = 11.72 angstrom and T(c) almost-equal-to 70 K respectively, and they became c = 11.70 angstrom and T(c) = 88 K after annealing in O2 at 400-degrees-C. Due to the slow deposition rates in the range 0.01-0.10 angstrom/s, only films with the c-axis perpendicular to the substrate surface were grown in situ in spite of the low temperature growth conditions. The full width at half-maximum (fwhm) of the (005) X-ray diffraction (XRD) peak was almost-equal-to 0.12-degrees and its rocking curve fwhm was almost-equal-to 0.35-degrees, which indicate together with the reflection high-energy electron diffraction (RHEED) that the in situ grown films were high-quality epitaxial single crystals.