Electrical characterization of chemically modified YBa2Cu3O7−x surfaces

Results on electrical characterization of YBa2Cu3O7−x thin-film surfaces treated with a Br/ethanol chemical etch are presented. Electrical measurements of YBa2Cu3O7−x/Au/Nb device structures fabricated using polycrystalline, post-annealed YBa2Cu3O7−x films with Br-etched surfaces, show improvements of approximately one or two orders of magnitude in current densities and resistivities (resistance-area products) relative to unetched devices. The existence of supercurrents in these structures has been confirmed by observation of the ac Josephson effect, and by magnetic field and temperature studies of the critical currents. The Br-etch process has produced 10×10 μm2 devices with critical current densities greater than 400 A/cm2 and resistivities as low as 4×10−7 Ω cm2.