Electrical properties of Nb-Mo Si2 -Nb Josephson junctions

We present a detailed study of the electrical properties of planar Nb-Mo Si2 -Nb Josephson junctions. The Nb-Mo Si2 -Nb junction is an excellent system to study proximity coupling in junctions with rigid superconductor/normal metal boundaries by precisely and independently controlling the barrier thickness and the temperature. With regard to applications, the Josephson properties are very reproducible, and the characteristic voltage can be tuned easily over more than two orders of magnitude while still maintaining a practical critical current density. The characteristic voltage can be controlled within ±5% at 4 K, with an exponential dependence on the barrier thickness. The proximity-coupled junction theory fits the temperature dependence of the critical current density, allowing us to quantitatively extract material parameters.