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Author Henrich, D.; Dorner,S.; Hofherr, M.; Il'in, K.; Semenov, A.; Heintze, E.; Scheffler, M.; Dressel, M.; Siegel, M.
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
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
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Author Il'in, K. S.; Currie, M.; Lindgren, M.; Milostnaya, I. I.; Verevkin, A. A.; Gol'tsman, G. N.; Sobolewski, R.
Title Quantum efficiency and time-domain response of superconducting NbN hot-electron photodetectors Type Journal Article
Year 1999 Publication IEEE Trans. Appl. Supercond. Abbreviated Journal IEEE Trans. Appl. Supercond.
Volume 9 Issue 2 Pages 3338-3341
Keywords NbN SSPD, SNSPD
Abstract We report our studies on the response of ultrathin superconducting NbN hot-electron photodetectors. We have measured the photoresponse of few-nm-thick, micron-size structures, which consisted of single and multiple microbridges, to radiation from the continuous-wave semiconductor laser and the femtosecond Ti:sapphire laser with the wavelength of 790 nm and 400 nm, respectively. The maximum responsivity was observed near the film's superconducting transition with the device optimally current-biased in the resistive state. The responsivity of the detector, normalized to its illuminated area and the coupling factor, was 220 A/W(3/spl times/10/sup 4/ V/W), which corresponded to a quantum efficiency of 340. The responsivity was wavelength independent from the far infrared to the ultraviolet range, and was at least two orders of magnitude higher than comparable semiconductor optical detectors. The time constant of the photoresponse signal was 45 ps, when was measured at 2.15 K in the resistive (switched) state using a cryogenic electro-optical sampling technique with subpicosecond resolution. The obtained results agree very well with our calculations performed using a two-temperature model of the electron heating in thin superconducting films.
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 1051-8223 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number Serial 1566
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Author Il'in, K. S.; Gol'tsman, G. N.; Voronov, B. M.; Sobolewski, Roman
Title Characterization of the electron energy relaxation process in NbN hot-electron devices Type Conference Article
Year 1999 Publication Proc. 10th Int. Symp. Space Terahertz Technol. Abbreviated Journal Proc. 10th Int. Symp. Space Terahertz Technol.
Volume Issue Pages 390-397
Keywords HEB mixers, SSPD, SNSPD, NbN films, Nb films
Abstract We report on transient measurements of electron energy relaxation in NbN films with 300-fs time resolution. Using an electro-optic sampling technique, we have studied the photoresponse of 3.5-nm-thick NbN films deposited on sapphire substrates and exposed to 100-fs-wide optical pulses. Our experimental data analysis was based on the two-temperature model and has shown that in our films at the superconducting transition 10.5 K the inelastic electron-phonon scattering time was about (111}+-__.2) ps. This response time indicated that the maximum intermediate-frequency band of a NbN hot-electron phonon-cooled mixer should reach (16+41-3) GHz if one eliminates the bolometric phonon-heating effect. We have suggested several ways to increase the effectiveness of phonon cooling to achieve the above intrinsic value of the NbN mixer bandwidth.
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 1576
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Author Il'in, K. S.; Verevkin, A. A.; Gol'tsman, G. N.; Sobolewski, R.
Title Infrared hot-electron NbN superconducting photodetectors for imaging applications Type Journal Article
Year 1999 Publication Supercond. Sci. Technol. Abbreviated Journal Supercond. Sci. Technol.
Volume 12 Issue 11 Pages 755-758
Keywords NbN SSPD, SNSPD
Abstract We report an effective quantum efficiency of 340, responsivity >200 A W-1 (>104 V W-1) and response time of 27±5 ps at temperatures close to the superconducting transition for NbN superconducting hot-electron photodetectors (HEPs) in the near-infrared and optical ranges. Our studies were performed on a few nm thick NbN films deposited on sapphire substrates and patterned into µm-size multibridge detector structures, incorporated into a coplanar transmission line. The time-resolved photoresponse was studied by means of subpicosecond electro-optic sampling with 100 fs wide laser pulses. The quantum efficiency and responsivity studies of our photodetectors were conducted using an amplitude-modulated infrared beam, fibre-optically coupled to the device. The observed picosecond response time and the very high efficiency and sensitivity of the NbN HEPs make them an excellent choice for infrared imaging photodetectors and input optical-to-electrical transducers for superconducting digital circuits.
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 0953-2048 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number Serial 1562
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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 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.
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 0003-6951 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number Serial 1579
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