Title :
NbCN Josephson junctions with AlN barriers
Author :
Thomasson, S.L. ; Murduck, J.M. ; Chan, H.
Author_Institution :
TRW, Redondo Beach, CA, USA
fDate :
3/1/1991 12:00:00 AM
Abstract :
Niobium carbonitride (NbCN) Josephson circuits can operate over a wider temperature range than either niobium or niobium nitride circuits. Higher operating temperature places NbCN technology more comfortably within the range of closed-cycle refrigerators, a key factor in aerospace applications. Tunnel junctions have been fabricated from NbCN films with transition temperatures up to 18 K. High-quality NbCN tunnel junction fabrication generally requires low stress films with roughness less than the barrier thickness (≈20 Å). Scanning tunneling microscopy was developed as a tool for measuring and optimizing film smoothness. Junctions formed in situ with AlN tunneling barriers show reproducible I-V characteristics. Unlike NbN, NbCN oxidizes readily, enabling junction definition by a modified SNAP process. This SNAP lithography technique successfully produced NbCn/AlN/NbCN junctions with Vm values (at 3 mV) up to 27 mV
Keywords :
aluminium compounds; niobium compounds; scanning tunnelling microscopy; superconducting junction devices; surface topography; 18 K; 20 Å; 27 mV; I-V characteristics; Josephson junctions; NbCN junction; NbCN-AlN-NbCN; SNAP lithography; SNAP process; aerospace applications; barrier thickness; closed-cycle refrigerators; film smoothness; junction definition; low stress films; roughness; scanning tunneling microscopy; transition temperatures; Circuits; Fabrication; Josephson junctions; Lithography; Microscopy; Niobium compounds; Refrigerators; Stress; Temperature distribution; Tunneling;
Journal_Title :
Magnetics, IEEE Transactions on
