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Author |
Beck, M.; Klammer, M.; Lang, S.; Leiderer, P.; Kabanov, V. V.; Gol'tsman, G. N.; Demsar, J. |
Title |
Energy-gap dynamics of superconducting NbN thin films studied by time-resolved terahertz spectroscopy |
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Journal Article |
Year |
2011 |
Publication |
Phys. Rev. Lett. |
Abbreviated Journal |
Phys. Rev. Lett. |
Volume |
107 |
Issue |
17 |
Pages |
4 |
Keywords |
NbN thin film, energy gap dynamics |
Abstract |
Using time-domain terahertz spectroscopy we performed direct studies of the photoinduced suppression and recovery of the superconducting gap in a conventional BCS superconductor NbN. Both processes are found to be strongly temperature and excitation density dependent. The analysis of the data with the established phenomenological Rothwarf-Taylor model enabled us to determine the bare quasiparticle recombination rate, the Cooper pair-breaking rate and the electron-phonon coupling constant, λ=1.1±0.1, which is in excellent agreement with theoretical estimates. |
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RPLAB @ gujma @ |
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641 |
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Manova, N. N.; Korneeva, Yu. P.; Korneev, A. A.; Slysz, W.; Voronov, B. M.; Gol'tsman, G. N. |
Title |
Superconducting NbN single-photon detector integrated with quarter-wave resonator |
Type |
Journal Article |
Year |
2011 |
Publication |
Tech. Phys. Lett. |
Abbreviated Journal |
Tech. Phys. Lett. |
Volume |
37 |
Issue |
5 |
Pages |
469-471 |
Keywords |
SSPD, SNSPD |
Abstract |
The spectral dependence of the quantum efficiency of superconducting NbN single-photon detectors integrated with quarter-wave resonators based on Si3N4, SiO2, and SiO layers has been studied. |
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RPLAB @ gujma @ |
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664 |
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Ozhegov, R. V.; Gorshkov, K. N.; Gol'tsman, G. N.; Kinev, N. V.; Koshelets, V. P. |
Title |
The stability of a terahertz receiver based on a superconducting integrated receiver |
Type |
Journal Article |
Year |
2011 |
Publication |
Supercond. Sci. Technol. |
Abbreviated Journal |
Supercond. Sci. Technol. |
Volume |
24 |
Issue |
3 |
Pages |
035003 |
Keywords |
SIS mixer, SIR, stability |
Abstract |
We present the results of stability testing of a terahertz radiometer based on a superconducting receiver with a SIS tunnel junction as the mixer and a flux-flow oscillator as the local oscillator. In the continuum mode, the receiver with a noise temperature of 95 K at 510 GHz measured over the intermediate frequency (IF) passband of 4-8 GHz offered a noise equivalent temperature difference of 10 ± 1 mK at an integration time of 1 s. We offer a method to significantly increase the integration time without the use of complex measurement equipment. The receiver observed a strong signal over a final detection bandwidth of 4 GHz and offered an Allan time of 5 s. |
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RPLAB @ gujma @ |
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705 |
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Seleznev, V. A.; Tarkhov, M. A.; Voronov, B. M.; Milostnaya, I. I.; Lyakhno, V. Yu; Garbuz, A. S.; Mikhailov, M. Yu; Zhigalina, O. M.; Gol'tsman, G. N. |
Title |
Deposition and characterization of few-nanometers-thick superconducting Mo-Re films |
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Journal Article |
Year |
2008 |
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Supercond. Sci. Technol. |
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Supercond. Sci. Technol. |
Volume |
21 |
Issue |
11 |
Pages |
115006 (1 to 6) |
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We report on the fabrication and investigation of few-nanometers-thick superconducting molybdenum-rhenium (Mo-Re) films intended for use in nanowire single-photon superconducting detectors (SSPDs). Mo-Re films were deposited on sapphire substrates by DC magnetron sputtering of an Mo(60)-Re(40) alloy target in an atmosphere of argon. The films 2-10 nm thick had critical temperatures (Tc) from 5.6 to 9.7 K. HRTEM (high-resolution transmission electron microscopy) analysis showed that the films had a homogeneous structure. XPS (x-ray photoelectron spectroscopy) analysis showed the Mo to Re atom ratio to be 0.575/0.425, oxygen concentration to be 10%, and concentration of other elements to be 1%. |
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RPLAB @ gujma @ |
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723 |
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Il'in, K. S.; Lindgren, M.; Currie, M. A.; Semenov, D.; Gol'tsman, G. N.; Sobolewski, Roman; Cherednichenko, S. I.; Gershenzon, E. M. |
Title |
Picosecond hot-electron energy relaxation in NbN superconducting photodetectors |
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Journal Article |
Year |
2000 |
Publication |
Appl. Phys. Lett. |
Abbreviated Journal |
Appl. Phys. Lett. |
Volume |
76 |
Issue |
19 |
Pages |
2752-2754 |
Keywords |
NbN HEB detectors, two-temperature model, IF bandwidth |
Abstract |
We report time-resolved characterization of superconducting NbN hot-electron photodetectors using an electro-optic sampling method. Our samples were patterned into micron-size microbridges from 3.5-nm-thick NbN films deposited on sapphire substrates. The devices were illuminated with 100 fs optical pulses, and the photoresponse was measured in the ambient temperature range between 2.15 and 10.6 K (superconducting temperature transition TC). The experimental data agreed very well with the nonequilibrium hot-electron, two-temperature model. The quasiparticle thermalization time was ambient temperature independent and was measured to be 6.5 ps. The inelastic electron–phonon scattering time Ï„e–ph tended to decrease with the temperature increase, although its change remained within the experimental error, while the phonon escape time Ï„es decreased almost by a factor of two when the sample was put in direct contact with superfluid helium. Specifically, Ï„e–ph and Ï„es, fitted by the two-temperature model, were equal to 11.6 and 21 ps at 2.15 K, and 10(±2) and 38 ps at 10.5 K, respectively. The obtained value of Ï„e–ph shows that the maximum intermediate frequency bandwidth of NbN hot-electron phonon-cooled mixers operating at TC can reach 16(+4/–3) GHz if one eliminates the bolometric phonon-heating effect. |
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0003-6951 |
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856 |
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