Application of textured IBAD-TiN buffer layers in coated conductor architectures

Abstract

Ion-beam assisted deposition (IBAD) is one of the major techniques for preparing highly textured templates for YBa2Cu3O7−x (YBCO) coated conductors. In most applications so far IBAD-MgO has been used. TiN is an alternative material for the IBAD process showing a textured nucleation similar to MgO. Different amorphous or nanocrystalline seed layers such as Al2O3, Y2O3 or Ta0.75Ni0.25 were found to be suitable for achieving strong cube textures in film thicknesses below 10 nm using reactive ion-beam assisted pulsed laser deposition. The biaxial texture was preserved to a higher thickness using homoepitaxial growth at higher temperatures. Different buffer layer architectures based on IBAD-TiN have been developed on Hastelloy substrates. An electrically conducting buffer layer stack was realized using a double layer of Au and Ir with a final Nb-doped SrTiO3 cap layer, enabling the epitaxial growth of YBCO on top. Alternatively, a robust simplified buffer architecture was studied using SrZrO3 directly on TiN, leading to highly textured YBCO layers.