Title :
Fabrication of Nb/Al-Al2O3/Nb junctions with extremely low leakage currents
Author :
Lichtenberger, A.W. ; McClay, C.P. ; Mattauch, R.J. ; Feldman, M.J. ; Pan, S.K. ; Kerr, A.R.
Author_Institution :
Dept. of Electr. Eng., Virginia Univ., Charlottesville, VA, USA
fDate :
3/1/1989 12:00:00 AM
Abstract :
Nb/Al-Al2O3/Nb trilayer films were deposited using DC magnetron sputtering guns in a UHV (ultrahigh vacuum) system which is capable of 5×10-10 Torr. SIS (superconductor-insulator-superconductor) junctions as small as 3.2×3.2 μm2 were isolated from the trilayer by standard photolithography. The junctions typically have Vm =70-90 mV at 4.2 K, while at 2.0 K, Vm is as large as 1 V. This corresponds to a subgap current of 0.15% of the quasiparticle current rise. The subgap leakage current is compared to the predictions of the BCS (Bardeen-Cooper-Schrieffer) theory. The specific capacitance is preliminarily measured to be 45±5 fF/μm2
Keywords :
aluminium; aluminium compounds; niobium; photolithography; sputtered coatings; superconducting junction devices; 2.0 K; 4.2 K; 5E-10 Torr; 70 to 90 mV; BCS; Bardeen-Cooper-Schrieffer; DC magnetron sputtering guns; Nb-Al-Al2O3-Nb; SIS; UHV; leakage currents; quasiparticle current rise; standard photolithography; subgap current; trilayer films; Fabrication; Guns; Josephson junctions; Lithography; Niobium; Sputtering; Superconducting devices; Superconducting films; Superconducting magnets; Vacuum systems;
Journal_Title :
Magnetics, IEEE Transactions on
