Electrical contact studies of chemically treated YBa sub 2 Cu sub 3 O sub 7 minus x surfaces

Results on electrical characterization of high T{sub {ital c}} thin film surfaces modified by different surface treatments are presented. In particular, this work examines the effect of a Br/ethanol chemical etch, which has previously been shown to remove surface contamination while preserving the Cu(+2) oxidation state. Electrical measurements of YBa{sub 2}Cu{sub 3}O{sub 7{minus}{ital x}}/Au/Nb contact structures fabricated using polycrystalline, post-annealed YBa{sub 2}Cu{sub 3}O{sub 7{minus}{ital x}} films with Br-etched surfaces, show improvements of approximately one to two orders of magnitude in contact current densities and resistivities (resistance-area products) relative to unetched contacts. The Br-etch process has produced 10{times}10 {mu}m{sup 2} contacts with contact current densities greater than 400 A/cm{sup 2} and R{sub n}A products as low as 4{times}10{sup {minus}7} {Omega}-cm{sup 2}.