X-RAY POLE FIGURE ANALYSIS ON FIBER TEXTURED EPITAXIAL NIOBIUM FILMS FOR SRF CAVITIES*

Single and large grain Nb films are of interest due to their potential for reduced cost to replace bulk Nb SRF cavities. The structural properties and SRF performance of Nb films obtained by coaxial energetic deposition (CED TM ) in a cathodic arc vacuum process are compared and discussed. The CED TM is a hybrid technique with both energetic ion deposition and implantation phase based on cathodic are plasma sources, which are copious generators of condensable energetic (20-200 eV), multiply charged ions from metal or alloy cathodes. X-ray diffraction (XRD) pole figures are used to investigate the grain orientations on Nb films grown at different substrate temperatures. The pole figures indicate good structural and electrical properties. The ratio of residual resistivity (RRR) dependence on a-plane sapphire substrate temperature shows RRR of ~129 and Tc=9.2K for 400 °C substrate, dropping to only ~4 for a room temperature substrate. This RRR figure of merit suggests good SRF performance in such Nb thin-films.