Microstructures of Y123 films on SrTiO3, LaGaO3 and LaAlO3

Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) have been used to study the microstructural features of YBa2Cu3O7 (hereafter referred to as Y123) films grown on various single crystal substrates by electron beam deposition. The films are all of high quality with the best observed Jc value being 107 A.cm-2 at 7K. Cross-sectional views in TEM have shown that the morphology of the film depends on its thickness. Thinner films (2500 angstrom) have a single layer of Y123 oriented with its c-axis perpendicular to the substrate while thicker films (8000 Angstrom) have this same c-axis perpendicular layer closest to the interface with a c-axis parallel layer above it. The interface between the film and the substrate is well defined in all cases with no amorphous region at the interface. Chemical analysis shows evidence of interdiffusion between the film and substrate