Very high-current-density Nb/AlN/Nb tunnel junctions for low-noise submillimeter mixers
Abstract
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.
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.Files
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Additional details
- Eprint ID
- 8933
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- CaltechAUTHORS:KAWapl00
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2007-10-02Created from EPrint's datestamp field
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2021-11-08Created from EPrint's last_modified field