Aging and its circumvention in rfhyphen;plasma oxidized Pbhyphen;alloy Josephson junctions

摘要

The aging phenomenon of Pbhyphen;alloy Josephson junctions is investigated and an effective method of circumventing it is presented. Junctions consist of Pbhyphen;alloy electrodes and a tunneling barrier formed by rfhyphen;plasma oxidation of the Pbhyphen;alloy. First, aging and annealinghyphen;driven change in normal tunneling resistance are compared to verify the usage of annealing as an experimental method for simulation and acceleration of aging. Next, process variables affecting the annealing change in junction characteristics are examined and their influence is described. The importance of the oxidehyphen;base electrode interface is confirmed and that of the counterelectrodehyphen;oxide interface is experimentally shown. Furthermore, possible changes in the oxide itself are discussed. Finally, on the basis of these studies, rfhyphen;plasma oxidation in a CO2atmosphere is employed and proven to be an effective method for circumventing the annealing change in the junction characteristics.