Multilayer Structures for High Temperature Superconducting Josephson Junctions
Original Publication Date: 1989-Jun-01
Included in the Prior Art Database: 2005-Jan-28
Fabrication of thin film Josephson tunnel junctions using high Tc oxide superconductors as electrodes is expected to be extremely difficult for several reasons. One is the very short coherence length (a few nm) which is expected for these high Tc materials, which makes them difficult to tunnel into (this currently limits the use of NbN as a counterelectrode in all NbN junctions, since it is difficult to grow a NbN electrode on top of an insulating tunnel barrier with adequate material perfection within a coherence length or so of the interface). Another is that the films tend to require high temperature (e.g., 900oC) anneal steps in order to have good superconducting properties, making fabrication of multilayer devices difficult.