Microbridge junctions, in the c-direction, with dimensions similar to lambda(c) have been fabricated. The c-axis microbridge (CAM) junction is formed between two superconducting layers of YBCO through a small hole in the insulator. The critical current and spread in critical currents of these junctions depends strongly on the oxygenation state of the junctions. The narrowest spread in I-c was found for overdoped samples. Using the CAM junction technology very low inductance (L similar to 5-15pH) SQUIDs have been demonstrated with dV/d Phi 1mV/Phi o at 50K. These junctions are attractive for use in SQUIDs because they are shielded from applied fields and can be integrated in low inductance, fully ground-planed structures. The tri-layer technology is particularly suitable for incorporating ground-planes on SQUID washer structures. First order gradiometric SQUIDs have been fabricated with high yield. Initial results are presented, at 77K, on the operation of these gradiometers in large fields, close to that of the earth.
