Growth Mechanism and Typical Grain Boundaries in YBa2Cu3O7−x Thin Films Grown on MgO Substrates

Abstract

Superconducting VBaCuO thin films grown in‐situ by magnetron sputtering on mechanically polished (001) MgO substrates are examined by transmission electron microscopy. The films appear to be crystalline consisting of three main types of epitaxial domains 90° ‐misoriented to each other, which causes the typical feature of these films, i.e., the high density of 90° rotation twin‐like boundaries. The surface of the films is not smooth resulting from the different thicknesses of the domains with different orientations. The microstructure of the films is explained by the growth rate anisotropy and the film nucleation peculiarities.

Microstructural Features of a-Axis Oriented YBa2Cu3O7-δ/PrBa2Cu3O7-δ/YBa2Cu3O7-δJunctions Studied by Transmission Electron Microscopy

“…This undesired orientation is completely lost for a total deposited thickness greater than 50 nm. The progressive loss of c-axis oriented grains is explained by the anisotropy of the growth rate in these compounds, a-axis grains growing 5 to 10 times faster than c-axis grains, as reported in [14]. Figure 3 The presence of Y203 inclusions in magnetron sputtered YBCO layers was reported in many different papers, see for instance [15][16][17].…”