Development of Nb/Al-oxide/Nb Josephson junction array at KRISS (voltage standard)

By using the selective niobium anodization process (SNAP) an all refractory 210-junction array was fabricated at KRISS. The array consists of Nb/Al-oxide/Nb junctions that have A=20 mu m*40 mu m. V/sub g/=2.8 mV, an average critical current approximately=650 mu A, and the spread of critical currents approximately=+or-5%. When operated at 94 GHz, the array generated zero-crossing steps up to 240 mV with stability times of more than 1 h.<
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