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Author Yagoubov, Pavel; Kroug, Matthias; Merkel, Harald; Kollberg, Erik; Schubert, Josef; Hübers, Heinz-Wilhelm
Title NbN hot electron bolometric mixers at frequencies between 0.7 and 3.1 THz Type Journal Article
Year 1999 Publication Supercond. Sci. Technol. Abbreviated Journal Supercond. Sci. Technol.
Volume 12 Issue 11 Pages 989-991
Keywords NbN HEB mixers
Abstract (up) The performance of NbN-based phonon-cooled hot electron bolometric (HEB) quasioptical mixers is investigated in the 0.7-3.1 THz frequency range. The devices are made from a 3.5-4 nm thick NbN film on high resistivity Si and integrated with a planar spiral antenna on the same substrate. The length of the bolometer microbridge is 0.1-0.2 µm; the width is 1-2 µm. The best results of the DSB receiver noise temperature measured at 1.5 GHz intermediate frequency are: 800 K at 0.7 THz, 1100 K at 1.6 THz, 2000 K at 2.5 THz and 4200 K at 3.1 THz. The measurements were performed with a far infrared laser as the local oscillator (LO) source. The estimated LO power requirement is less than 500 nW at the receiver input. First results on spiral antenna polarization measurements are reported.
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Series Volume Series Issue Edition
ISSN 0953-2048 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number Serial 295
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Author Okunev, 0.; Dzardranov, A.; Gol'tsman, G.; Gershenzon, E.
Title Performances of hot—electron superconducting mixer for frequencies less than the gap energy: NbN mixer for 100 GHz operation Type Conference Article
Year 1995 Publication Proc. 6th Int. Symp. Space Terahertz Technol. Abbreviated Journal Proc. 6th Int. Symp. Space Terahertz Technol.
Volume Issue Pages 247-253
Keywords NbN HEB mixers
Abstract (up) The possibilities to improve the parameters of the 100 GHz NbN HEB superconducting waveguide mixers have been studied. The device consists of a signal strip 1 gm wide by 2 Am long made of 40 A thick NbN film. The best operation point was found at 5 K, where the mixer bandwidth made up 1.5-2 GHz and the total loss diminished down to 8 dB. The critical current density has been increased up to " 40 6 A/cm 2 , the noise temperature of the receiver (DSB) has reduced down to 450 K and the local oscillator power has decreased down to -.4).1 mcV.
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Notes Approved no
Call Number Serial 1625
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Author Smirnov, K.; Divochiy, A.; Vakhtomin, Y.; Morozov, P.; Zolotov, P.; Antipov, A.; Seleznev, V.
Title NbN single-photon detectors with saturated dependence of quantum efficiency Type Journal Article
Year 2018 Publication Supercond. Sci. Technol. Abbreviated Journal Supercond. Sci. Technol.
Volume 31 Issue 3 Pages 035011 (1 to 8)
Keywords NbN SSPD, SNSPD
Abstract (up) The possibility of creating NbN superconducting single-photon detectors with saturated dependence of quantum efficiency (QE) versus normalized bias current was investigated. It was shown that the saturation increases for the detectors based on finer films with a lower value of Rs300/Rs20. The decreasing of Rs300/Rs20 was related to the increasing influence of quantum corrections to conductivity of superconductors and, in turn, to the decrease of the electron diffusion coefficient. The best samples have a constant value of system QE 94% at Ib/Ic ~ 0.8 and wavelength 1310 nm.
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Series Volume Series Issue Edition
ISSN 0953-2048 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number Serial 1232
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Author Lindgren, M.; Currie, M.; Zeng, W.-S.; Sobolewski, R.; Cherednichenko, S.; Voronov, B.; Gol'tsman, G. N.
Title Picosecond response of a superconducting hot-electron NbN photodetector Type Journal Article
Year 1998 Publication Appl. Supercond. Abbreviated Journal Appl. Supercond.
Volume 6 Issue 7-9 Pages 423-428
Keywords NbN SSPD, SNSPD
Abstract (up) The ps optical response of ultrathin NbN photodetectors has been studied by electro-optic sampling. The detectors were fabricated by patterning ultrathin (3.5 nm thick) NbN films deposited on sapphire by reactive magnetron sputtering into either a 5×10 μm2 microbridge or 25 1 μm wide, 5 μm long strips connected in parallel. Both structures were placed at the center of a 4 mm long coplanar waveguide covered with Ti/Au. The photoresponse was studied at temperatures ranging from 2.15 K to 10 K, with the samples biased in the resistive (switched) state and illuminated with 100 fs wide laser pulses at 395 nm wavelength. At T=2.15 K, we obtained an approximately 100 ps wide transient, which corresponds to a NbN detector response time of 45 ps. The photoresponse can be attributed to the nonequilibrium electron heating effect, where the incident radiation increases the temperature of the electron subsystem, while the phonons act as the heat sink. The high-speed response of NbN devices makes them an excellent choice for an optoelectronic interface for superconducting digital circuits, as well as mixers for the terahertz regime. The multiple-strip detector showed a linear dependence on input optical power and a responsivity =3.9 V/W.
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ISSN 0964-1807 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number Serial 1584
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Author Il’in, K. S.; Milostnaya, I. I.; Verevkin, A. A.; Gol’tsman, G. N.; Gershenzon, E. M.; Sobolewski, R.
Title Ultimate quantum efficiency of a superconducting hot-electron photodetector Type Journal Article
Year 1998 Publication Appl. Phys. Lett. Abbreviated Journal Appl. Phys. Lett.
Volume 73 Issue 26 Pages 3938-3940
Keywords NbN SSPD, SNSPD
Abstract (up) The quantum efficiency and current and voltage responsivities of fast hot-electron photodetectors, fabricated from superconducting NbN thin films and biased in the resistive state, have been shown to reach values of 340, 220 A/W, and 4×104 V/W,

respectively, for infrared radiation with a wavelength of 0.79 μm. The characteristics of the photodetectors are presented within the general model, based on relaxation processes in the nonequilibrium electron heating of a superconducting thin film. The observed, very high efficiency and sensitivity of the superconductor absorbing the photon are explained by the high multiplication rate of quasiparticles during the avalanche breaking of Cooper pairs.
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Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0003-6951 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number Serial 1579
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