MATERIALS ISSUES RELATED TO THE FABRICATION OF HTS SQUIDS

A number of materials related problems have hindered the development o f a reproducible process for the fabrication of high-quality SQUIDs an d magnetometers. In this paper we discuss the use of GdBa2Cu3O7 and YB a2Cu3O7 thin films for the fabrication of step-edge and bicrystal magn etometers and how materials selection can influence issues such as rep roducibility, yield and noise performance. Magnetometers with noise pe rformance as low as 63 ft/root Hz have been made with variations in ju nction parameters (I-c and R-n) that are as low as 25% on-chip and 57% from chip-to-chip.