STACKED JOSEPHSON-JUNCTION BASED ON NB SI SUPERLATTICE/

We report on the technology and basic electrical properties of ten-fol d stacked Nb/Si/Nb Josephson junction (JJ). The problem of making a la rge number of stacked JJs with identical properties was solved by meta llic superlattice preparation technology. The uniformity of Si barrier s thickness was examined by low angle X-ray diffraction and cross-sect ional transmission electron microscopy. To prevent pinholes in the Si barriers the Nb/Si superlattice was sputtered at the regime at which s moothing of interfacial roughness occurs. The stacked junction exhibit both ac and dc Josephson effects. In the I-c(B) diffraction pattern t here is an extra periodicity of about 2 - 3 G in addition to a larger period of about 21 G.