Preferentially oriented epitaxial Y-Ba-Cu-O films prepared by the ion beam sputtering method

Abstract

Preferentially oriented epitaxial Y-Ba-Cu-O films were prepared on (100) SrTiO3 substrates by oxygen reactive ion beam sputtering. The epitaxial orientations were varied by controlling both substrate temperature and oxygen parital pressure. c-axis oriented films tended to be formed at higher substrate temperatures (>620 °C) and lower oxygen pressures (<3×10−3 Torr). In contrast, a/c- and a-axis oriented films were formed at lower substrate temperatures (<600 °C) and higher oxygen pressures (>3×10−3 Torr). The best Tc (end) of 82 K was observed in one of the c-axis oriented film without post-annealing. The tendency for preferential orientation can be well understood in terms of the lattice mismatch between the substrate and the film, the lattice constants of which depend on oxygen deficiency.