ELECTROMIGRATION EFFECTS IN E-BEAM JUNCTIONS

We have investigated electromigration effects in electron beam damaged junctions. Electromigration is performed by applying DC bias currents with current densities of around 1 MA/cm(2) to the junctions at room temperature. They are made by patterning off axis laser deposited film s with optical lithography and Ar ion milling and subsequently direct damage with a 350 kV electron beam. It has been found that for bias cu rrents in the range between 0.9 MA/cm(2) and 1.1 MA/cm(2) the magnetic field behaviour and the current-voltage characteristics of the juncti ons can be reversibly modified by electromigration. The critical tempe rature of the junctions depends linearly on the electromigration time. Taking the geometry and heating effects into account, the data can be explained by a rearrangement of oxygen in the chains during electromi gration, while the junction properties are mostly determined by oxygen vacancies and interstitials in the planes.