High-resistance HTS edge junctions for digital circuits

We have investigated factors affecting the resistance of edge-geometry HTS weak links, including SNS junctions with Co-doped Y-Ba-Cu-O as a normal metal interlayer. We have also studied devices with no deposited interlayer in which the weak link is produced by ion beam surface damage or by controlled disorder near the base electrode-counterelectrode interface. For each of these weak links several parameters, including the base electrode material and the deposition conditions of the normal metal and counterelectrode, are found to have strikingly large effects on device resistance. Controlling these factors has enabled the fabrication of high-quality, high-resistance (/spl ap/1 Ohm) SNS edge junctions with one-sigma I/sub c/ spreads down to 6% in 10-junction series arrays. The junctions without deposited interlayers exhibit electrical characteristics and parameter spreads approaching the best results obtained with the Co-YBCO SNS devices.