ISSTT Proceedings

ISSTT Proceedings

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An 850 GHz Waveguide Receiver Using a Tuned Nb SIS Tunnel Junction Fabricated on a 1 µm Si3N4 Membrane

Authors:
J.W. Kooi, M.S. Chan, P. Schaffer, B. Bumble, H.G. LeDuc, C.K. Walker, T.G. Phillips
Abstract:
We report on a 850 GHz SIS heterodyne receiver employing a tuned niobium tunnel junction with a current density of 14kA/cm² fabricated on a 1 µm Si3N4 supporting membrane. Since the mixer is meant to be operated well above the superconducting gap frequency of niobium (2[Delta]/h [approx. equal to] 690 GHz) special care has been taken to minimize transmission line loss. We have therefore used junctions with an integrated radial stub RF matching network to tune out the large shunt susceptance of the junction and minimize the niobium film absorption loss. Scale model measurements of the waveguide embedding impedance have been made to aid in the design of the choke structure and RF matching network. Detailed Fourier Transform Spectrometer measurements of tuned junctions show response up to 1000 GHz and indicate that the absorption loss in the niobium film is in the order of 4-7 dB at 850 GHz.
Categories:
SIS Mixers
Year:
1996
Session:
1
Full-text:
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Page Number(s):
86-102