Shot noise beyond the Tucker theory in niobium tunnel junction mixers

P. Dieleman, T. M. Klapwijk

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The electrical and shot-noise characteristics of high-current-density niobium superconductor–insulator–superconductor (SIS) tunnel junctions suitable for heterodyne detection of THz radiation are studied. It is found that a significant part of the current at voltages V<2Δ/e is carried via barrier defects (pinholes). Due to the transport mechanism in these pinholes, the shot noise is considerably increased. The data presented clarify an often-observed discrepancy between measured and expected heterodyne mixer noise temperatures and predict a 25% increase in the receiver noise temperature of Nb SIS heterodyne detectors at 1 THz.
Original languageEnglish
Pages (from-to)1653 - 1655
Number of pages3
JournalApplied Physics Letters
Issue number13
Publication statusPublished - 1998



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