Study of Nb/Nb_xSi_1-x/Nb Josephson junction arrays

Owing to the adjustable characteristics and superior etching properties of co-sputtered Nb_xSi_1-x film, we are trying to fabricate Nb/Nb_xSi_1-x/Nb Josephson junction arrays for voltage standard. It is important to find the suitable Nb_xSi_1-x barrier for the junctions. Josephson junctions with different barrier content are fabricated. Current-voltage characteristics are measured and analyzed. It is demonstrated in this paper that critical current can be adjusted by using different barrier content and thickness. Shapiro steps of five hundred junctions in series are observed.