초록 열기/닫기 버튼
We fabricated superconducting quantum interference devices (SQUIDs) based on Nb Josephson junctions, and characterized thekey parameters of the SQUIDs. The SQUIDs are double relaxation oscillation SQUIDs (DROSs) having larger flux-to-voltagetransfer coefficient than the standard DC-SQUIDs. SQUID sensors were fabricated by using Nb junction technology consisted of aDC magnetron sputtering and a conventional photolithography process. In multichannel SQUID systems for whole-headmagnetoencephalography measurement with a helmet-type SQUID array, we need about 336 SQUID sensors for each system. Inthis paper, we fabricated a few hundred SQUID sensors, measured the critical current, flux modulation voltage and decided if eachtested SQUID can be used for the multichannel systems. As the criterion for the acceptance of the sensors, we chose the criticalcurrent and amplitude of the modulation voltage to be 8 ㎂ and 80 ㎶, respectively. The average critical current of the SQUIDs was10.58 ㎂. The typical flux noise of the SQUIDs with input coil shorted was 2 μΦ0/√Hz at white region.
