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Very high-current-density Nb/AlN/Nb tunnel junctions for low-noise submillimeter mixers

Kawamura, Jonathan and Miller, David and Chen, Jian and Zmuidzinas, Jonas and Bumble, Bruce and LeDuc, Henry G. and Stern, Jeff A. (2000) Very high-current-density Nb/AlN/Nb tunnel junctions for low-noise submillimeter mixers. Applied Physics Letters, 75 (15). pp. 2119-2121. ISSN 0003-6951. doi:10.1063/1.126272.

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We have fabricated and tested submillimeter-wave superconductor–insulator–superconductor (SIS) mixers using very high-current-density Nb/AlN/Nb tunnel junctions (Jc[approximate]30 kA cm–2). The junctions have low-resistance-area products (RNA[approximate]5.6 Omega µm2), good subgap-to-normal resistance ratios Rsg/RN[approximate]10, and good run-to-run reproducibility. From Fourier transform spectrometer measurements, we infer that omegaRNC = 1 at 270 GHz. This is a factor of 2.5 improvement over what is generally available with Nb/AlOx/Nb junctions suitable for low-noise mixers. The AlN-barrier junctions are indeed capable of low-noise operation: we measure an uncorrected double-sideband receiver noise temperature of TRX = 110 K at 533 GHz for an unoptimized device. In addition to providing wider bandwidth operation at lower frequencies, the AlN-barrier junctions will considerably improve the performance of THz SIS mixers by reducing rf loss in the tuning circuits.

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Additional Information:©2000 American Institute of Physics. (Received 27 October 1999; accepted 14 February 2000) This work was supported in part by NASA/JPL and its Center for Space Microelectronics Technology, by NASA Grant Nos. NAG5-4890, NAGW-107, and NAG2-1068, by the NASA/USRA SOFIA instrument development program, and by the Caltech Submillimeter Observatory (NSF Grant No. AST-9615025). One of the authors (J.C.) acknowledges support from the Japanese Ministry of Education, Science, Sports, and Culture.
Subject Keywords:niobium; aluminium compounds; superconductor-insulator-superconductor mixers; submillimetre wave mixers; superconducting device noise
Issue or Number:15
Record Number:CaltechAUTHORS:KAWapl00
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:8933
Deposited By: Archive Administrator
Deposited On:02 Oct 2007
Last Modified:08 Nov 2021 20:54

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