Development of fast-switching Nb/Al/Nb SNS junctions for the ac Josephson voltage standard

We report here the current development status of our Nb/Al/Nb SNS Josephson junctions for a programmable voltage standard. The morphology and the electrical parameters of these junctions are strongly dependent on the Al deposition rate. The rf and magnetic field behaviour is also reported, together with preliminary data about the uniformity and reproducibility of the series arrays made with this technology.