Barriers Formation on YBa₂Cu₃O_y Thin Film Using CF₄ Plasma Fluorination

We investigate the surface structure and composition of
YBa₂Cu₃O_y (YBCO) thin film modified by CF₄ plasma fluorination. In addition to the absorption of hydrocarbons, chemical reactions of the YBCO surface take place during CF₄ plasma treatment. Various x-ray photoelectron spectroscopic data are reported and discussed, and the existence of a thin barrier is confirmed, which homogeneously covers the edge of the base YBCO film in our interface engineering Josephson junction. Measurements of Auger electron spectroscopic data and the resistance versus temperature indicate that the barrier is a controllable-insulating layer.