Structural and morphological characterization of high quality Y 1Ba 2Cu 3O x epitaxial films by atomic force and high resolution scanning electron microscopies

Abstract

Epitaxial Y 1Ba 2Cu 3O x (YBCO) films with very smooth surface morphology and excellent superconducting properties ( T c = 92 K, J c = 10 7 A cm −2) were grown on {100} SrTiO 3 and {100} MgO substrates by pulsed laser deposition (PLD). The film surfaces were structurally and morphologically characterized using atomic force microscopy (AFM) and high resolution scanning electron microscopy (HRSEM). Both microscopies revealed different types of film growth and outgrowths which consist of epitaxial and non-epitaxial grains. Some of the outgrowths consisted of high densities of small insulating nanoparticles and, since it appears from HRSEM that they are distributed throughout the interior of the film, they would seem to have high enough densities to become potential candidates for flux pinning sites. The results have also shown that the outgrowths and other surface features formed on the YBCO films are sensitive to composition and deposition conditions. Observations of surface topography as studied by both AFM and HRSEM are discussed in the present paper.