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Author Yang, J.K.W.; Kerman, A.J.; Dauler, E.A.; Cord, B.; Anant, V.; Molnar, R.J.; Berggren, K.K. openurl 
  Title Suppressed critical current in superconducting nanowire single-photon detectors with high fill-factors Type Journal Article
  Year 2009 Publication IEEE Trans. Appl. Supercond. Abbreviated Journal (down)  
  Volume 19 Issue 3 Pages 318-322  
  Keywords SNSPD  
  Abstract In this work we present a new fabrication process that enabled the fabrication of superconducting nanowire single photon detectors SNSPD with fill-factors as high as 88% with gaps between nanowires as small as 12 nm. This fabrication process combined high-resolution electron-beam lithography with photolithography. Although this work was motivated by the potential of increased detection efficiency with higher fill-factor devices, test results showed an unexpected systematic suppression in device critical currents with increasing fill-factor.  
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  Notes Approved no  
  Call Number RPLAB @ gujma @ Serial 677  
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Author Tretyakov, Ivan; Ryabchun, Sergey; Finkel, Matvey; Maslennikov, Sergey; Maslennikova, Anna; Kaurova, Natalia; Lobastova, Anastasia; Voronov, Boris; Gol'tsman, Gregory doi  openurl
  Title Ultrawide noise bandwidth of NbN hot-electron bolometer mixers with in situ gold contacts Type Journal Article
  Year 2011 Publication IEEE Trans. Appl. Supercond. Abbreviated Journal (down)  
  Volume 21 Issue 3 Pages 620-623  
  Keywords NbN HEB mixer bandwidth  
  Abstract We report a noise bandwidth of 7 GHz in the new generation of NbN hot-electron bolometer (HEB) mixers that are being developed for the space observatory Millimetron. The HEB receiver driven by a 2.5-THz local oscillator offered a noise temperature of 600 K in a 50-MHz final detection bandwidth. As the filter center frequency was swept this value remained nearly constant up to the cutoff frequency of the cryogenic amplifier at 7 GHz. We believe that such a low value of the noise temperature is due to reduced radio frequency (RF) loss at the interface between the superconducting film and the gold contacts. We have also performed gain bandwidth measurements at the superconducting transition on HEB mixers with various lengths and found them to be in excellent agreement with the results of the analytical and numerical models developed for the HEB mixer with both diffusion and phonon cooling of hot electrons.  
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  Area Expedition Conference  
  Notes Approved no  
  Call Number RPLAB @ gujma @ Serial 716  
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Author Lobanov, Y.; Tong, E.; Blundell, R.; Hedden, A.; Voronov, B.; Gol'tsman, G. doi  openurl
  Title Large-signal frequency response of an HEB mixer: from 300 MHz to terahertz Type Journal Article
  Year 2011 Publication IEEE Trans. Appl. Supercond. Abbreviated Journal (down)  
  Volume 21 Issue 3 Pages 628-631  
  Keywords waveguide NbN HEB mixers  
  Abstract We present a study of the large signal frequency response of an HEB mixer over a wide frequency range. In our experiments, we have subjected the HEB mixer to incident electromagnetic radiation from 0.3 GHz to 1 THz. The mixer element is an NbN film deposited on crystalline quartz. The mixer chip is mounted in a waveguide cavity, coupled to free space with a diagonal horn. At microwave frequencies, electromagnetic radiation is applied through the coaxial bias port of the mixer block. At higher frequencies the input signal passes via the diagonal horn feed. At each frequency, the incident power is varied and a family of I-V curves is recorded. From the curves we identify 3 distinct regimes of operation of the mixer separated by the phonon relaxation frequency and the superconducting energy gap frequency observed at about 3 GHz and 660 GHz respectively. In this paper, we will present observed curves and discuss the results of our experiment.  
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  Notes Approved no  
  Call Number RPLAB @ gujma @ Serial 719  
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Author Kawakami, A; Saito, S.; Hyodo, M. openurl 
  Title Fabrication of nano-antennas for superconducting Infrared detectors Type Journal Article
  Year 2011 Publication IEEE Trans. Appl. Supercond. Abbreviated Journal (down)  
  Volume 21 Issue 3 Pages 632-635  
  Keywords optical antennas, NbN/MgO/NbN/TiN/Al HEB, dipole antennas, IR, infrared  
  Abstract To improve the response performance of superconducting infrared detectors, we have developed a fabrication process for nano-antennas. A nano-antenna consists of a dipole antenna, and a superconducting thin film strip placed in the antenna's center. By measuring the transition temperature of the superconducting strips, we confirmed that their superconductivity maintained a good condition after the nano-antenna fabrication process. We also evaluated nano-antenna characteristics using Fourier transform infrared spectroscopy. The evaluated antenna length and width were respectively set at around 2400 nm and 400 nm, and the antennas were placed at intervals of several micrometers around the area of 1 mm2 . In an evaluation of spectral transmission characteristics, clear absorption caused by antenna effects was observed at around 1400 cm-1. High polarization dependencies were also observed.  
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  Area Expedition Conference  
  Notes Approved no  
  Call Number Serial 761  
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Author Zhang, Jin; Slysz, W.; Verevkin, A.; Okunev, O.; Chulkova, G.; Korneev, A.; Lipatov, A.; Gol'tsman, G. N.; Sobolewski, R. doi  openurl
  Title Response time characterization of NbN superconducting single-photon detectors Type Journal Article
  Year 2003 Publication IEEE Trans. Appl. Supercond. Abbreviated Journal (down)  
  Volume 13 Issue 2 Pages 180-183  
  Keywords SSPD jitter, SNSPD jitter  
  Abstract We report our time-resolved measurements of NbN-based superconducting single-photon detectors. The structures are meander-type, 10-nm thick, and 200-nm wide stripes and were operated at 4.2 K. We have shown that the NbN devices can count single-photon pulses with below 100-ps time resolution. The response signal pulse width was about 150 ps, and the system jitter was measured to be 35 ps.  
  Address  
  Corporate Author Thesis  
  Publisher IEEE Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number Serial 1058  
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Author Skalare, A.; McGrath, William R.; Echternach, P. M.; Leduc, H. G.; Siddiqi, I.; Verevkin, A.; Prober, D. E. doi  openurl
  Title Aluminum hot-electron bolometer mixers at submillimeter wavelengths Type Journal Article
  Year 2001 Publication IEEE Trans. Appl. Supercond. Abbreviated Journal (down)  
  Volume 11 Issue 1 Pages 641-644  
  Keywords Al HEB mixer, contacts, interface, in situ, in-situ, Aluminium HEB mixer  
  Abstract Diffusion-cooled aluminum hot-electron bolometer (HEB) mixers are of interest for low-noise high resolution THz-frequency spectroscopy within astrophysics. Al HEB mixers offer operation with an order of magnitude less local oscillator power, higher intermediate frequency bandwidth and potentially lower noise than competing devices made from other materials. We report on mixer experiments at 618 GHz with devices fabricated from films with sheet resistances in the range from about 55 Ω down to about 9 Ω per square. Intermediate frequency bandwidths of up to 3 GHz were measured (1 μm long device), with absorbed local oscillator power levels of 0.5 to 6 nW and mixer conversion up to -21.5 dB. High input coupling efficiency implies that the electrons in the device are able to thermalize before escaping from the device. It was found that the long coherence length complicates mixer operations due to the proximity of the contact pads. Also, saturation at the IF frequency may be a concern for this type of device, and warrants further studies.  
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  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1051-8223 ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number ref919426b Serial 1061  
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Author Gupta, D.; Kadin, A. M. doi  openurl
  Title Single-photon-counting hotspot detector with integrated RSFQ readout electronics Type Journal Article
  Year 1999 Publication IEEE Trans. Appl. Supercond. Abbreviated Journal (down)  
  Volume 9 Issue 2 Pages 4487-4490  
  Keywords RSFQ, SSPD, SNSPD  
  Abstract Absorption of an infrared photon in an ultrathin film (such as 10-nm NbN) creates a localized nonequilibrium hotspot on the submicron length scale and sub-ns time scale. If a strip /spl sim/1 /spl mu/m wide is biased in the middle of the superconducting transition, this hotspot will lead to a resistance pulse with amplitude proportional to the energy of the incident photon. This resistance pulse, in turn, can be converted to a current pulse and inductively coupled to a SQUID amplifier with a digitized output, operating at 4 K or above. A preliminary design analysis indicates that this data can be processed on-chip, using ultrafast RSFQ digital circuits, to obtain a sensitive infrared detector for wavelengths up to 10 /spl mu/m and beyond, with bandwidth of 1 GHz, that counts individual photons and measures their energy with 25 meV resolution. This proposed device combines the speed of a hot-electron bolometer with the single-photon-counting ability of a transition-edge microcalorimeter, to obtain an infrared detector with sensitivity, speed, and spectral selectivity that are unmatched by any alternative technology.  
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  Notes Approved no  
  Call Number Serial 1080  
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Author Larrey, V.; Villegier, J. -C.; Salez, M.; Miletto-Granozio, F.; Karpov, A. doi  openurl
  Title Processing and characterization of high Jc NbN superconducting tunnel junctions for THz analog circuits and RSFQ Type Journal Article
  Year 1999 Publication IEEE Trans. Appl. Supercond. Abbreviated Journal (down)  
  Volume 9 Issue 2 Pages 3216-3219  
  Keywords RSFQ, NbN, SIS  
  Abstract A generic NbN Superconducting Tunnel Junctions (STJ) technology has been developed using conventional substrates (Si and SOI-SIMOX) for making THz spectrometers including SIS receivers and RSFQ logic gates. NbN/MgO/NbN junctions with area of 1 /spl mu/m/sup 2/, Jc of 10 kA/cm/sup 2/ and low sub-gap leakage current (Vm>25 mV) are currently obtained from room temperature sputtered multilayers followed by a post-annealing at 250/spl deg/C. Using a thin MgO buffer layer deposited underneath the NbN electrodes, ensures lower NbN surface resistance values (Rs=7 /spl mu//spl Omega/) at 10 GHz and 4 K. Epitaxial NbN [100] films on MgO [100] with high gap frequency (1.4 THz) have also been achieved under the same deposition conditions at room temperature. The NbN SIS has shown good I-V photon induced steps when LO pumped at 300 GHz. We have developed an 8 levels Al/NbN multilayer process for making 1.5 THz SIS mixers (including Al antennas) on Si membranes patterned in SOI-SIMOX. Using the planarization techniques developed at the Si-MOS CEA-LETI Facility, we have also demonstrated on the possibility of extending our NbN technology to high level RSFQ circuit integration with 0.5 /spl mu/m/sup 2/ junction area, made on large area substrates (up to 8 inches).  
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  Notes Approved no  
  Call Number Serial 1081  
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Author Samsonova, Alena; Zolotov, Philipp; Baeva, Elmira; Lomakin, Andrey; Titova, Nadezhda; Kardakova, Anna; Goltsman, Gregory doi  openurl
  Title Signatures of surface magnetic disorder in thin niobium films Type Journal Article
  Year 2021 Publication IEEE Trans. Appl. Supercond. Abbreviated Journal (down)  
  Volume Issue Pages 1-1  
  Keywords Temperature measurement, Temperature dependence, Superconducting magnets, Superconducting transition temperature, Substrates, Resistance, Scattering  
  Abstract We present our studies on the evolution of the normal and superconducting properties with thickness of thin Nb films with a low level of non-magnetic disorder (kFl 150 for the thickest film in the set). The analysis of the superconducting behavior points to the presence of magnetic moments, hidden in the native oxide on the surface of Nb films. Using the Abrikosov-Gorkov theory, we obtain the density of surface magnetic moments of 1013 cm-2, which is in agreement with the previously reported data for Nb films.  
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  Corporate Author Thesis  
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  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1051-8223 ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number Serial 1162  
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