A New Microbridge with an Improved I-V Curve

The I-V curves of microbridges of uniform thickness and given geometry are calculated, and the results are in good agreement with those of Pb thin-film microbridges with the corresponding geometries. Using this result, we have designed a microbridge of new geometry with metallic balls at the edges of the bridge part which prevent the normal state from expanding into the electrodes when the electric current is increased. A very simple technique for fabricating this new microbridge is described. With the new microbridge, more Shappiro steps have been observed than with conventional microbridges, up to a voltage as high as 0.7 mV.