Germanium-overcoated niobium Dayem bridges

Abstract
Overcoating constriction microbridges with semiconducting germanium provides additional thermal conductivity at liquid‐helium temperatures to reduce the effects of self‐heating in these Josephson junctions. Microwave‐induced steps were observed in the IV characteristics of an overcoated Dayem bridge fabricated in a 15‐nm‐thick niobium film; at 4.2 K (TcT=2.6 K), at least 20 steps could be counted. No steps were observed in the IV characteristics of the bridge prior to overcoating. In addition, the germanium overcoat can protect against electrical disturbances at room temperature.