Low temperature molecular beam epitaxial growth of DyBaCuO superconducting thin films

Superconducting DyBa2Cu3O6.7 (orthorhombic I phase) thin films were grown in situ on NdGaO3 (001) and (100) substrates at 400–440 °C by molecular beam epitaxy method. The c-axis lattice constant and the critical temperature were c=11.72 Å and Tc∼70 K, respectively, and they became c=11.70 Å and Tc=88 K after annealing in O2 at 400 °C. Due to the slow deposition rates in the range of 0.01–0.10 Å/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 of the (005) x-ray diffraction peak rocking curve was ∼0.35°, indicating together with the reflection high-energy electron diffraction that the in situ grown films were high quality epitaxial single crystals.