Josephson junctions and DC SQUIDS based on Nb/Al technology.
A process for fabricating high-quality Josephson junctions and DC SQUIDs on basis of Nb/Al technology has been developed. DC magnetron sputtering is used for the deposition of the metal layers and the barrier is formed by thermal oxidation of the Al-layer. The junction area of 5 microns x 5 microns is obtained using anodisation. Three types of Josephson tunnel junctions have been prepared: standard Nb/Al, AlO kappa/Nb, symmetric Nb/Al, AlO kappa, Al/Nb and Nb/Al, AlO kappa/AlO kappa/Nb, the latter having a double oxide layer. We performed current-voltage and conductance-voltage measurements at different temperatures and special attention was paid to the noise behaviour. Gap and sub-gap parameters as well as barrier parameters are presented. Three different DC SQUID configurations were developed on basis of the Nb/Al Josephson junctions. The measured characteristics of the standard Tesche-Clarke DC SQUID, the resistively shunted SQUID and the inductively shunted SQUID are compared with special attention being paid to the noise properties. A 19-channel DC SQUID magnetometer with standard and/or resistively-shunted DC SQUIDs is under construction.
Flokstra
J
J
University of Twente, Faculty of Applied Physics, Enschede, The Netherlands.
Adelerhof
D J
DJ
Houwman
E P
EP
Veldhuis
D
D
Rogalla
H
H
D000535:Aluminum; D004867:Equipment Design; D006801:Humans; D008280:Magnetics; D009556:Niobium
D009556:Niobium; D000535:Aluminum