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Author Henrich, D.; Dorner,S.; Hofherr, M.; Il'in, K.; Semenov, A.; Heintze, E.; Scheffler, M.; Dressel, M.; Siegel, M. openurl 
  Title Broadening of hot-spot response spectrum of superconducting NbN nanowire single-photon detector with reduced nitrogen content Type Journal Article
  Year 2012 Publication Abbreviated Journal J. Appl. Phys.  
  Volume 112 Issue Pages (up)  
  Keywords SSPD, SNSPD, magnetron sputtering, spectrum, NbN film, nitrogen concentration  
  Abstract The spectral detection efficiency and the dark count rate of superconducting nanowire

single-photon detectors (SNSPD) have been studied systematically on detectors made from thin

NbN films with different chemical compositions. Reduction of the nitrogen content in the 4 nm

thick NbN films results in a decrease of the dark count rates more than two orders of magnitude

and in a red shift of the cut-off wavelength of the hot-spot SNSPD response. The observed

phenomena are explained by an improvement of uniformity of NbN films that has been confirmed

by a decrease of resistivity and an increase of the ratio of the measured critical current to the

depairing current. The latter factor is considered as the most crucial for both the cut-off

wavelength and the dark count rates of SNSPD. Based on our results we propose a set of criteria

for material properties to optimize SNSPD in the infrared spectral region. VC 2012 American

Institute of Physics. [http://dx.doi.org/10.1063/1.4757625]
 
  Address  
  Corporate Author D. Henrich, S. Dorner, M. Hofherr, K. Il'in, A. Semenov, E. Heintze, M. Scheffler, M. Dressel, M. Siegel Thesis  
  Publisher Place of Publication Editor  
  Language English Summary Language Original Title Broadening of hot-spot response spectrum of superconducting NbN nanowire single-photon detector with reduced nitrogen content  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number RPLAB @ seleznev @ Serial 877  
Permanent link to this record
 

 
Author Semenov, A.; Engel, A.; Il'in, K.; Gol'tsman, G.; Siegel, M.; Hübers, H.-W. url  doi
openurl 
  Title Ultimate performance of a superconducting quantum detector Type Journal Article
  Year 2003 Publication Eur. Phys. J. Appl. Phys. Abbreviated Journal Eur. Phys. J. Appl. Phys.  
  Volume 21 Issue 3 Pages (up) 171-178  
  Keywords NbN SSPD, SNSPD  
  Abstract We analyze the ultimate performance of a superconducting quantum detector in order to meet requirements for applications in near-infrared astronomy and X-ray spectroscopy. The detector exploits a combined detection mechanism, in which avalanche quasiparticle multiplication and the supercurrent jointly produce a voltage response to a single absorbed photon via successive formation of a photon-induced and a current-induced normal hotspot in a narrow superconducting strip. The response time of the detector should increase with the photon energy providing energy resolution. Depending on the superconducting material and operation conditions, the cut-off wavelength for the single-photon detection regime varies from infrared waves to visible light. We simulated the performance of the background-limited infrared direct detector and X-ray photon counter utilizing the above mechanism. Low dark count rate and intrinsic low-frequency cut-off allow for realizing a background limited noise equivalent power of 10−20 W Hz−1/2 for a far-infrared direct detector exposed to 4-K background radiation. At low temperatures, the intrinsic response time of the counter is rather determined by diffusion of nonequilibrium electrons than by the rate of energy transfer to phonons. Therefore, thermal fluctuations do not hamper energy resolution of the X-ray photon counter that should be better than 10−3 for 6-keV photons. Comparison of new data obtained with a Nb based detector and previously reported results on NbN quantum detectors support our estimates of ultimate detector performance.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1286-0042 ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number Serial 534  
Permanent link to this record
 

 
Author Semenov, A. D.; Gol’tsman, G. N. url  doi
openurl 
  Title Nonthermal mixing mechanism in a diffusion-cooled hot-electron detector Type Journal Article
  Year 2000 Publication J. Appl. Phys. Abbreviated Journal J. Appl. Phys.  
  Volume 87 Issue 1 Pages (up) 502-510  
  Keywords NbN HEB mixers, nonthermal  
  Abstract We present an analysis of a diffusion-cooled hot-electron detector fabricated from clean superconducting material with low transition temperature. The distinctive feature of a clean material, i.e., material with large electron mean free path, is a relatively weak inelastic electron scattering that is not sufficient for the establishment of an elevated thermodynamic electron temperature when the detector is subjected to irradiation. We propose an athermal model of a diffusion-cooled detector that relies on suppression of the superconducting energy gap by the actual dynamic distribution of excess quasiparticles. The resistive state of the device is caused by the electric field penetrating into the superconducting bridge from metal contacts. The dependence of the penetration length on the energy gap delivers the detection mechanism. The sources of the electric noise are equilibrium fluctuations of the number of thermal quasiparticles and frequency dependent shot noise. Using material parameters typical for A1, we evaluate performance of the device in the heterodyne regime at terahertz frequencies. Estimates show that the mixer may have a noise temperature of a few quantum limits and a bandwidth of a few tens of GHz, while the required local oscillator power is in the μW range due to ineffective suppression of the energy gap by quasiparticles with high energies.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0021-8979 ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number Serial 1558  
Permanent link to this record
 

 
Author Danerud, M.; Winkler, D.; Lindgren, M.; Zorin, M.; Trifonov, V.; Karasik, B. S.; Gol’tsman, G. N.; Gershenzon, E. M. url  doi
openurl 
  Title Nonequilibrium and bolometric photoresponse in patterned YBa2Cu3O7−δ thin films Type Journal Article
  Year 1994 Publication J. Appl. Phys. Abbreviated Journal J. Appl. Phys.  
  Volume 76 Issue 3 Pages (up) 1902-1909  
  Keywords YBCO HTS HEB detector, nonequilibrium response  
  Abstract Epitaxial laser deposited YBa2Cu3O7−δ films of ∼50 nm thickness were patterned into detectors consisting of ten parallel 1 μm wide strips in order to study nonequilibrium and bolometric effects. Typically, the patterned samples had critical temperatures around 86 K, transition widths around 2 K and critical current densities above 1×106A/cm2 at 77 K. Pulsed laser measurements at 0.8 μm wavelength (17 ps full width at half maximum) showed a ∼30 ps response, attributed to electron heating, followed by a slower bolometric decay. Amplitude modulation in the band fmod=100 kHz–10 GHz of a laser with wavelength λ=0.8 μm showed two different thermal relaxations in the photoresponse. Phonon escape from the film (∼3 ns) is the limiting process, followed by heat diffusion in the substrate. Similar relaxations were also seen for λ=10.6 μm. The photoresponse measurements were made with the film in the resistive state and extended into the normal state. These states were created by supercritical bias currents. Measurements between 75 and 95 K (i.e., from below to above Tc) showed that the photoresponse was proportional to dR/dT for fmod=1 MHz and 4 GHz. The fast response is limited by the electron‐phonon scattering time, estimated to 1.8 ps from experimental data. The responsivity both at 0.8 and 10.6 μm wavelength was ∼1.2 V/W at fmod=1 GHz and the noise equivalent power was calculated to 1.5×10−9 WHz−1/2 for the fast response.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0021-8979 ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number Serial 1637  
Permanent link to this record
 

 
Author Gousev, Yu. P.; Gol'tsman, G. N.; Semenov, A. D.; Gershenzon, E. M.; Nebosis, R. S.; Heusinger, M. A.; Renk, K. F. doi  openurl
  Title Broadband ultrafast superconducting NbN detector for electromagnetic radiation Type Journal Article
  Year 1994 Publication J. Appl. Phys. Abbreviated Journal J. Appl. Phys.  
  Volume 75 Issue 7 Pages (up) 3695-3697  
  Keywords NbN HEB  
  Abstract An ultrafast detector that is sensitive to radiation in a broad spectral range from submillimeter waves to visible light is reported. It consists of a structured NbN thin film cooled to a temperature below Tc (∼11 K). Using 20 ps pulses of a GaAs laser, we observed signal pulses with both rise and decay time of about 50 ps. From the analysis of a mixing experiment with submillimeter radiation we estimate an intrinsic response time of the detector of ∼12 ps. The sensitivity was found to be similar for the near‐infrared and submillimeter radiation. Broadband sensitivity and short response time are attributed to a quasiparticle heating effect.  
  Address  
  Corporate Author Thesis  
  Publisher 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 252  
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