Microstructure of epitaxial ErBa2Cu3O7−x thin films grown on MgO (100) substrates by rf magnetron sputtering

Abstract

The microstructural properties of superconducting ErBa2Cu3O7−x films on single-crystal MgO substrates are studied by transmission electron microscopy. The as-grown films are single-crystal-like and are composed of subgrains of 0.1–0.2 μm in size. Due to annealing, the dislocations at the subgrain boundaries disappeared. The annealed films are epitaxial with either the a or the b axis of the ErBa2Cu3O7−x unit cell along 〈100〉 directions of the MgO substrate. The stress caused by lattice mismatch is relaxed by the formation of misfit dislocations at the film/substrate interface.

Growth Mechanism of Sputtered Films of YBa 2 Cu 3 O 7 Studied by Scanning Tunneling Microscopy

“…Several types of defects have been identified in films of YBa2Cu307 by transmission electron microscopy (TEM), x-ray diffraction and ion-beam channeling, including stacking faults in the ab planes (1-4), latticemismatch edge dislocations (3,5,6), various types of twin boundaries, antiphase boundaries (3)(4) and low-and high-angle grain boundaries (4,7). There is, however, no general agreement as to the nature of the defects that are primarily responsible for the superior flux-pinning properties of epitaxial thin films, as compared with bulk or polycrystalline materials.…”