Direct-coupled high-T_c thin film SQUIDs using step-edge weak-link junctions

Direct-coupled single-layer thin film SQUID magnetometers are the most reproducible high-Tc magnetometers fabricated to-date. They also serve as a good model for early identification of critical device and fabrication needs for system applications. A step-edge weak-link junction is a single-layer junction technology that allows easy lithographic definition of device position. In this article we discuss the basic technologies involved in the fabrication of single-layer SQUID devices, as well as some issues in operating such SQUIDs in an ambient, unshielded environment. © 1996.