Extension of the operating range of superconducting microbridges

We have reduced the self-heating of microbridges by attaching the actual thin (0.1 μm) bridge to a thick (1 μm) film. Two different fabricating procedures have been followed, based on scratching with a diamond point. Contrary zo expectation, based on previous experimental evidence, Sn microbridges as long as 0.7 μmand 1 μm wide were found to show microwave (9 and 35 GHz) induced steps, periodically varying with power, in a temperature interval 0.3 < T/Tc< 0.97. Good results were also obtained with Al. These results support the idea that previous experiments by various authors have been considerably influenced by self-heating, not taken into account in their interpretation of the results, and that it is possible to use microbridges for device applications at temperatures far below Tc.