High-quality [1 0 0] and [1 1 0] YBa2Cu3O7−δ films for Josephson tunnelling

Abstract YBa 2 Cu 3 O 7−δ /PrBa 2 Cu 3 O 7−δ (YBCO/PBCO) bilayers [1 0 0] and [1 1 0] oriented are in situ grown by a reactive co-deposition technique on SrTiO 3 single-crystal substrates. Atomic force microscopy and transmission electron microscopy images, X-rays diffraction patterns have been used to investigate their structural properties and surface morphology, in order to optimize their characteristics. To obtain high-quality YBCO [1 0 0] and [1 1 0] layers, we first deposit a PBCO template layer at 630°C, followed by a YBCO film at 630–750°C, with a growth rate of 0.063 nm/s. They display a very high crystallinity and a surface roughness as low as 0.5 nm for YBCO/PBCO [1 0 0] bilayer at a 1 μm 2 scale. Reproducible Josephson junctions have been made on these films.