MICROBRIDGES IN HIGH-TC SUPERCONDUCTORS - HIGH ICRN PRODUCTS

Intentionally weakened links were produced by diffusing Al or Cu into grain boundaries of microbridges of high Tc superconductors. Thin and narrow (70-130 nm) strips of Al and Cu were deposited across previously patterned microbridges and diffused into them for a short time at 300-450 °C. Dc and rf Josephson properties were registered. ICRN products of up to 3 mV were measured at 4.2 K for a laser ablated Bi-Pb-Ca-Sr-Cu-O film (Tc = 64 K) and 0.9 mV at 77 K for an Y-Ba-Cu-O film (Tc = 87 K). Problems with electron resist residues could be circumvented by depositing a thin layer of Ag in-situ on the superconductor before any processing. © 1990.