SUBMICRON ION-BEAM MODIFICATION OF HIGH-T-C SUPERCONDUCTING BRIDGES

We have investigated the modification of high-ir, superconducting film structures due to ion beam irradiation using a mask technology. The Y Ba2Cu3O7 (YBCO) and GdBa2Cu3O7 (GBCO) thin film microbridges were cove red with electron resist (PMMA) masks. Then, a submicron slit was patt erned by e-beam lithography. The high-T-c bridges were modified by irr adiation with argon ions. Fluence and energy of the ions could be vari ed and the change in the electrical properties of the modified regions have been measured. For suitable values of ion energy and fluence we measured Shapiro steps in the current-voltage curves under microwave i rradiation for a temperature range of a few Kelvin just below the crit ical temperature. We found a modulation of the Shapiro steps with incr easing microwave power and compared the power dependence to Josephson and flux flow behaviour. The Monte-Carlo program TRIM was used for cha racterization of the ion solid interaction, especially for the estimat ion of range, damage distribution and straggling in dependence on geom etry.