Y-Ba-Cu-O film growth on Y/sub 2/O/sub 3/ buffered and nonbuffered SrTiO/sub 3/ single crystals using precursor films including fluoride

A fluoride compound, BaF/sub 2/, was used in the ex situ post-reaction process which was effective in the preparation of thick YBa/sub 2/Cu/sub 3/O/sub 7-x/ (YBCO) films over 1 micrometers for coated conductors. We investigated the YBCO film growth on SrTiO/sub 3/ single crystal with and without Y/sub 2/O/sub 3/ buffer layers using BaF/sub 2/. In order to suppress the reaction between the YBCO precursor films and the Y/sub 2/O/sub 3/ buffer layer, we controlled the atmospheric pressure and changed the evaporation materials to obtain precursor films which included fluoride. No water vapor was introduced during the heat treatment. The epitaxy c-axis oriented YBCO films, with 0.3 /spl mu/m thickness, were successfully grown on both the Y/sub 2/O/sub 3/ buffered and nonbuffered SrTiO/sub 3/ single crystals using Y, BaF/sub 2/ and Cu as evaporation sources. We also deposited YBCO films on both substrates using evaporation sources, YF/sub 3/, Ba and Cu. An appreciably different result has been obtained using YF/sub 3/ compared to that using BaF/sub 2/.