Title :
Fabrication and mixer performance of Nb/Al double-barrier junctions
Author :
Lehnert, T. ; Sheng-Cai Shi ; Noguchi, T.
Author_Institution :
Inst. de Radio Astron. Millimetrique, IRAM, St.-Martin-d´Heres, France
fDate :
6/1/1995 12:00:00 AM
Abstract :
Specific difficulties of the fabrication of Nb/Al double-barrier junctions with high current density (10 kA/cm/sup 2/) and small area (1-3 /spl mu/m/sup 2/) are discussed and possible solutions are presented. The problem of nonuniform areas of the two superposed junctions was circumvented by introducing a loading effect in the etching process. Strong backbending of the I/V-curve was reduced by increasing the thickness of the Nb layer between the two superposed junctions. In a mixer experiment in the 100 GHz frequency band a broad-band response of the double-barrier device was obtained with a minimum receiver noise temperature of 45 K at 115 GHz.<>
Keywords :
aluminium; electron device manufacture; etching; millimetre wave mixers; niobium; superconductor-insulator-superconductor mixers; 115 GHz; I/V-curve; Nb-Al; Nb/Al double-barrier junctions; broad-band response; current density; etching; fabrication; loading effect; mixer; nonuniform areas; receiver noise temperature; Argon; Current density; Electrodes; Etching; Fabrication; Frequency; Josephson junctions; Mixers; Niobium; Wiring;
Journal_Title :
Applied Superconductivity, IEEE Transactions on
