Properties of Nb3Ge variable-thickness bridges

Variable-thickness bridges (VTB’s) using Nb3Ge film have been investigated. In order to form a very short length bridge in the direction of the current flow and cause little damage to the superconducting properties, slant evaporation and anodization technique was used. The current–voltage characteristics, temperature dependence of critical current response to microwave irradiation were measured. One of the VTB’s whose length is estimated to be less than 100 nm showed microwave induced steps over a wide temperature range, from 6 to 18.3 K. The resistively shunted Josephson junction model is found to explain the behavior of the device well.