Identification of the misfit dislocations at YBa2Cu3O7-δ/SrTiO3 interface using moire fringe contrast

Misfit dislocations at YBa2Cu3O7-delta (YBCO)/SrTiO3 (STO) interfaces were studied to understand effects which could be responsible for the high interfacial J(c) in YBCO thin films. In YBCO films with thickness ranging from 5 to 100 nm, the interfacial structures (e.g. misfit dislocations) of YBCO/STO were investigated using moire fringe contrast in plan-view transmission electron microscopy (TEM). The observed moire pattern has a spacing of 17 nm which corresponds to the lattice mismatch between the YBCO a lattice spacing and the cubic STO lattice constant. As the YBCO thickness reaches 100 nm, twin structures dominate the image contrast. Our observations indicate that the moire pattern originates from the lattice mismatch between the substrate and the orthorhombic phase of YBCO. (c) 2006 Elsevier B.V. All rights reserved.