Strong cube-textured titanium nitride conductive films directly on flexible metal substrate

Highlights: • Simple structure of cube-textured conductive TiN by direct deposition on metal foil. • Ion pre-treatment enables cube texture of TiN directly on polycrystalline substrate. • Ion Beam Assisted Deposition for TiN films with in-plane texture spread of only 5.6°. Single crystal-like titanium nitride (TiN) by ion beam assisted deposition (IBAD) method is a potential conductive and thermally-stable template for growing highly-oriented REBa₂Cu₃O_7−x (RE = rare earth) superconductor tapes as well as optoelectronics on flexible metal substrates. Previously, amorphous seed layers such as Al₂O₃ and Y₂O₃ were necessary for the biaxially-textured film growth by IBAD. Such nonconductive seed layers prevent an electrically-conductive path between functional film and bottom metal substrate such as flexible, electro-polished Hastelloy (EPH). An approach of Argon ion (Ar⁺) pre-treatment of EPH surface, followed by roll-to-roll IBAD process has been developed for a simplified architecture of cube-textured TiN directly on flexible metal substrate. Strong cube-textured TiN films with out-of-plane texture spread of 1.8° and in-plane texture spread of 5.6° were obtained by IBAD technique on flexible Hastelloy substrate without any intervening layers; this provides a conductive template for functional layers. Also, the ion pretreatment step is easily achieved in an IBAD system which simplifies the fabrication process.