FABRICATION OF HIGH-QUALITY NB AL/ALOX/NB STACKED JOSEPHSON-JUNCTIONS/

We have fabricated stacked Josephson junctions from a double trilayer structure deposited sequentially with the intermediate Nb layer slight ly thicker than lambda(L). The lower electrode geometry was patterned by a sequence of Reactive Ion Etching and sputter-etching operations, while the junctions were defined by anodic oxidation of the top and th e intermediate electrodes. We measured from the I-V characteristic the quasiparticle losses, finding V(m) congruent-to 65 mV. Moreover we fo und that the critical currents in the two junctions of each stack are similar within less than ten percent and the magnetic field patterns a re very regular.