Fabrication and electromagnetic properties of planar variable-thickness S-N-S microbridges

A fully optical version of the oblique evaporation technique through undercut photoresist stencils developed by Dolan is used to fabricate planar variable-thickness S-N-S microbridges. An experimental study of the static and dynamic behaviour of Pb-Cu-Pb devices is reported. IcRN-products are found in good agreement with the Likharev theory and its modifications. In the shortest microbridges we find IcRN- values of the order of the limiting value 2Δpb(O)/e. The I-V curves show hysteresis only at the lowest temperatures of our experiments and exhibit sharp quantum steps when the samples are exposed to microwave radiation.