Sidewall shunted overdamped NbN–MgO–NbN Josephson junctions Available to Purchase

A sidewall shunting method is demonstrated to realize overdamped (i.e., nonhysteretic) current-voltage $(IV)$ characteristics in superconductor-insulator-superconductor (SIS) junctions. Unlike the conventional layout of shunted SIS junctions, patterning a normal metal shunt on one of the sides of the junction considerably reduces the parasitic inductive path and leaves more area on a chip for active components. Using a conventional optical lithography route we have fabricated sidewall shunted SIS junctions of various sizes from NbN–MgO–NbN trilayers on MgO and oxidized Si substrates. In our experiment the effective shunting resistance is realized by a tunnel contact between the shunt metal and the base electrode via a thin layer of insulating MgO. The results of our electrical measurements verify the overdamped nature of the junctions shunted in this manner.