Experimental Study of the Plasma Fluorination of Y-Ba-Cu-O ThinFilms

We have experimentally studied the surface modifications of the
Y-Ba-Cu-O (YBCO) thin films by CF₄ plasma. The intensity of the plasma fluorination was controlled by changing the biasing voltage and the time of the plasma treatment. Microstructure analyses reveal that the oxygen content of the YBCO thin films had been changed. Transport measurements of sufficient fluorinated YBCO films imply that the films had been changed totally into an oxygen-deficient semi-conducting state. From these experimental results we believe that the plasma fluorination is a quite useful method to form controllable thin barrier layer in fabricating interface engineered junctions and to form a stable narrow weak-link region in fabricating planar superconductor-normal-superconductor junctions.