Growth behavior and surface morphology of homoepitaxial YBa2Cu3O7−δ thin films on flux‐grown single crystals

Atomically flat terraces and steps with a height of one c‐axis lattice parameter have been observed with atomic force microscopy (AFM) on the surface of a flux‐grown YBa2Cu3O7−δ (YBCO) single crystal. Homoepitaxial growth of YBCO on the flux‐grown single crystal has been investigated using reflection high‐energy electron diffraction (RHEED). Initial stage of the RHEED intensity oscillation without anomalous peaks usually observed in heteroepitaxial growth suggests epitaxial growth of YBCO on the substrate surface from the beginning of deposition. A surface image of AFM for the homoepitaxial film reveals coalescent step‐like structures and two‐dimensional islands of one c‐axis height on the growing surface of YBCO. The observed RHEED oscillation and AFM image are consistent with the two‐dimensional nucleation growth of the film.