Molecular beam epitaxy growth and microstructure of thin superconducting Bi 2Sr 2CaCu 2O x films

Abstract

The microstructure of molecular beam epitaxy (MBE) grown Bi 2Sr 2CaCu 2O x films has been studied by reflection high-energy electron diffraction (RHEED), high-resolution electron microscopy (HREM) and X-ray diffraction (XRD). In situ recorded RHEED images of as-grown films show two-dimensional growth, 90° oriented domains (twist domains) and an incommensurate superstructure. For the first time, the presence of both 2201 and 2223 stacking faults in Bi 2Sr 2CaCu 2O x thin films is reported. These local structural defects are not easily observed by standard XRD techniques. To examine the structure of the films quantitatively, a general one-dimensional XRD model was fitted to the experimental XRD data. The model considered changes in peak intensities, positions and line-widths, and thus allowed a quantitative determination of the structural properties of the high- T c superconducting thin films.