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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 |
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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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Delacour, C.; Claudon, J.; Poizat, J.-Ph.; Pannetier, B.; Bouchiat, V.; de Lamaestre, R. Espiau; Villegier, J.-C.; Tarkhov, M.; Korneev, A.; Voronov, B.; Gol'tsman, G. |
Title |
Superconducting single photon detectors made by local oxidation with an atomic force microscope |
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Journal Article |
Year |
2007 |
Publication |
Appl. Phys. Lett. |
Abbreviated Journal |
Appl. Phys. Lett. |
Volume |
90 |
Issue ![sorted by Issue field, ascending order (up)](img/sort_asc.gif) |
19 |
Pages |
191116 (1 t0 3) |
Keywords |
SSPD |
Abstract |
The authors present a fabrication technique of superconducting single photon detectors made by local oxidation of niobium nitride ultrathin films. Narrow superconducting meander lines are obtained by direct writing of insulating niobium oxynitride lines through the films using voltage-biased tip of an atomic force microscope. Due to the 30nm resolution of the lithographic technique, the filling factor of the meander line can be made substantially higher than detector of similar geometry made by electron beam lithography, thus leading to increased quantum efficiency. Single photon detection regime of these devices is demonstrated at 4.2K.
The authors thank J.-P. Maneval for stimulating discussions. This work has been partly supported by ACI Nanoscience from French Ministry of Research, D.G.A., by Grant No. 02.445.11.7434 of Russian Ministry of Education and Science, and by the European Commission under project “SINPHONIA,” Contract No. NMP4-CT-2005-16433. |
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0003-6951 |
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423 |
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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 |
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Appl. Phys. Lett. |
Abbreviated Journal |
Appl. Phys. Lett. |
Volume |
76 |
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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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Yagoubov, P.; Kroug, M.; Merkel, H.; Kollberg, E.; Gol'tsman, G.; Svechnikov, S.; Gershenzon, E. |
Title |
Noise temperature and local oscillator power requirement of NbN phonon-cooled hot electron bolometric mixers at terahertz frequencies |
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Journal Article |
Year |
1998 |
Publication |
Appl. Phys. Lett. |
Abbreviated Journal |
Appl. Phys. Lett. |
Volume |
73 |
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19 |
Pages |
2814-2816 |
Keywords |
NbN HEB mixers, noise temperature, local oscillator power |
Abstract |
In this letter, the noise performance of NbN-based phonon-cooled hot electron bolometric quasioptical mixers is investigated in the 0.55–1.1 THz frequency range. The best results of the double-sideband <cd><2018>DSB<cd><2019> noise temperature are: 500 K at 640 GHz, 600 K at 750 GHz, 850 K at 910 GHz, and 1250 K at 1.1 THz. The water vapor in the signal path causes significant contribution to the measured receiver noise temperature around 1.1 THz. The devices are made from 3-nm-thick NbN film on high-resistivity Si and integrated with a planar spiral antenna on the same substrate. The in-plane dimensions of the bolometer strip are typically 0.2Ï«2 um. The amount of local oscillator power absorbed in the bolometer is less than 100 nW. |
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911 |
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Loudkov, D.; Tong, C. Y. E.; Blundell, R.; Kaurova, N.; Grishina, E.; Voronov, B.; Gol'tsman, G. |
Title |
An investigation of the performance of the superconducting HEB슠mixer as a function of its RF슠embedding impedance |
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Journal Article |
Year |
2005 |
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IEEE Trans. Appl. Supercond. |
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15 |
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2 |
Pages |
472-475 |
Keywords |
HEB mixer |
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IEEE |
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371 |
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Gol'tsman, G. N.; Karasik, B. S.; Okunev, O. V.; Dzardanov, A. L.; Gershenzon, E. M.; Ekstrom, H.; Jacobsson, S.; Kollberg, E. |
Title |
NbN hot electron superconducting mixers for 100 GHz operation |
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Journal Article |
Year |
1995 |
Publication |
IEEE Trans. Appl. Supercond. |
Abbreviated Journal |
IEEE Trans. Appl. Supercond. |
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5 |
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2 |
Pages |
3065-3068 |
Keywords |
NbN HEB mixers |
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NbN is a promising superconducting material for hot-electron superconducting mixers with an IF bandwidth larger than 1 GHz. In the 1OO GHz frequency range, the following parameters were obtained for 50 /spl Aring/ thick NbN films at 4.2 K: receiver noise temperature (DSB) /spl sim/1000 K; conversion loss /spl sim/10 dB; IF bandwidth /spl sim/1 GHz; and local oscillator power /spl sim/1 /spl mu/W. An increase of the critical current of the NbN film, increased working temperature, and a better mixer matching may allow a broader IF bandwidth up to 2 GHz, reduced conversion losses down to 3-5 dB and a receiver noise temperature (DSB) down to 200-300 K. |
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1051-8223 |
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About LO power required |
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255 |
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Sobolewski, R.; Verevkin, A.; Gol'tsman, G.N.; Lipatov, A.; Wilsher, K. |
Title |
Ultrafast superconducting single-photon optical detectors and their applications |
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Journal Article |
Year |
2003 |
Publication |
IEEE Trans. Appl. Supercond. |
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13 |
Issue ![sorted by Issue field, ascending order (up)](img/sort_asc.gif) |
2 |
Pages |
1151-1157 |
Keywords |
NbN SSPD, SNSPD |
Abstract |
We present a new class of ultrafast single-photon detectors for counting both visible and infrared photons. The detection mechanism is based on photon-induced hotspot formation, which forces the supercurrent redistribution and leads to the appearance of a transient resistive barrier across an ultrathin, submicrometer-width, superconducting stripe. The devices were fabricated from 3.5-nm- and 10-nm-thick NbN films, patterned into <200-nm-wide stripes in the 4 /spl times/ 4-/spl mu/m/sup 2/ or 10 /spl times/ 10-/spl mu/m/sup 2/ meander-type geometry, and operated at 4.2 K, well below the NbN critical temperature (T/sub c/=10-11 K). Continuous-wave and pulsed-laser optical sources in the 400-nm-to 3500-nm-wavelength range were used to determine the detector performance in the photon-counting mode. Experimental quantum efficiency was found to exponentially depend on the photon wavelength, and for our best, 3.5-nm-thick, 100-/spl mu/m/sup 2/-area devices varied from >10% for 405-nm radiation to 3.5% for 1550-nm photons. The detector response time and jitter were /spl sim/100 ps and 35 ps, respectively, and were acquisition system limited. The dark counts were below 0.01 per second at optimal biasing. In terms of the counting rate, jitter, and dark counts, the NbN single-photon detectors significantly outperform their semiconductor counterparts. Already-identified applications for our devices range from noncontact testing of semiconductor CMOS VLSI circuits to free-space quantum cryptography and communications. |
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1051-8223 |
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509 |
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Kawamura, J. H.; Tong, C.-Y.E.; Blundell, R.; Cosmo Papa, D.; Hunter, T. R.; Gol'tsman, G.; Cherednichenko, S.; Voronov, B.; Gershenzon, E. |
Title |
An 800 GHz NbN phonon-cooled hot-electron bolometer mixer receiver |
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Journal Article |
Year |
1999 |
Publication |
IEEE Trans. Appl. Supercond. |
Abbreviated Journal |
IEEE Trans. Appl. Supercond. |
Volume |
9 |
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2 |
Pages |
3753-3756 |
Keywords |
NbN HEB mixers |
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We describe a heterodyne receiver developed for astronomical applications to operate in the 350 /spl mu/m atmospheric window. The waveguide receiver employs a superconductive NbN phonon-cooled hot-electron bolometer mixer. The double sideband receiver noise temperature closely follows 1 kGHz/sup -1/ across 780-870 GHz, with the intermediate frequency centered at 1.4 GHz. The conversion loss is about 15 dB. The receiver was installed for operation at the University of Arizona/Max Planck Institute for Radio Astronomy Submillimeter Telescope facility. The instrument was successfully used to conduct test observations of a number of celestial sources in a number of astronomically important spectral lines. |
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1051-8223 |
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288 |
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Meledin, D.; Tong, C. Y.-E.; Blundell, R.; Kaurova, N.; Smirnov, K.; Voronov, B.; Gol'tsman, G. |
Title |
Study of the IF bandwidth of NbN HEB mixers based on crystalline quartz substrate with an MgO buffer layer |
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Journal Article |
Year |
2003 |
Publication |
IEEE Trans. Appl. Supercond. |
Abbreviated Journal |
IEEE Trans. Appl. Supercond. |
Volume |
13 |
Issue ![sorted by Issue field, ascending order (up)](img/sort_asc.gif) |
2 |
Pages |
164-167 |
Keywords |
NbN HEB mixer |
Abstract |
In this paper, we present the results of IF bandwidth measurements on 3-4 nm thick NbN hot electron bolometer waveguide mixers, which have been fabricated on a 200-nm thick MgO buffer layer deposited on a crystalline quartz substrate. The 3-dB IF bandwidth, measured at an LO frequency of 0.81 THz, is 3.7 GHz at the optimal bias point for low noise receiver operation. We have also made measurements of the IF dynamic impedance, which allow us to evaluate the intrinsic electron temperature relaxation time and self-heating parameters at different bias conditions. |
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341 |
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Semenov, A. D.; Hübers, Heinz-Wilhelm; Richter, H.; Birk, M.; Krocka, M.; Mair, U.; Vachtomin, Yu. B.; Finkel, M. I.; Antipov, S. V.; Voronov, B. M.; Smirnov, K. V.; Kaurova, N. S.; Drakinski, V. N.; Gol'tsman, G. N. |
Title |
Superconducting hot-electron bolometer mixer for terahertz heterodyne receivers |
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Journal Article |
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2003 |
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IEEE Trans. Appl. Supercond. |
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Volume |
13 |
Issue ![sorted by Issue field, ascending order (up)](img/sort_asc.gif) |
2 |
Pages |
168-171 |
Keywords |
NbN HEB mixers |
Abstract |
We present recent results showing the development of superconducting NbN hot-electron bolometer mixer for German receiver for astronomy at terahertz frequencies and terahertz limb sounder. The mixer is incorporated into a planar feed antenna, which has either logarithmic spiral or double-slot configuration, and backed on a silicon lens. The hybrid antenna had almost frequency independent and symmetric radiation pattern slightly broader than expected for a diffraction limited antenna. At 2.5 THz the best 2200 K double side-band receiver noise temperature was achieved across a 1 GHz intermediate frequency bandwidth centred at 1.5 GHz. For this operation regime, a receiver conversion efficiency of -17 dB was directly measured and the loss budget was evaluated. The mixer response was linear at load temperatures smaller than 400 K. Implementation of the MgO buffer layer on Si resulted in an increased 5.2 GHz gain bandwidth. The receiver was tested in the laboratory environment by measuring a methanol emission line at 2.5 THz. |
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343 |
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Gol'tsman, G.; Minaeva, O.; Korneev, A.; Tarkhov, M.; Rubtsova, I.; Divochiy, A.; Milostnaya, I.; Chulkova, G.; Kaurova, N.; Voronov, B.; Pan, D.; Kitaygorsky, J.; Cross, A.; Pearlman, A.; Komissarov, I.; Slysz, W.; Wegrzecki, M.; Grabiec, P.; Sobolewski, R. |
Title |
Middle-infrared to visible-light ultrafast superconducting single-photon detectors |
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Journal Article |
Year |
2007 |
Publication |
IEEE Trans. Appl. Supercond. |
Abbreviated Journal |
IEEE Trans. Appl. Supercond. |
Volume |
17 |
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2 |
Pages |
246-251 |
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SSPD, SNSPD |
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We present an overview of the state-of-the-art of NbN superconducting single-photon detectors (SSPDs). Our devices exhibit quantum efficiency (QE) of up to 30% in near-infrared wavelength and 0.4% at 5 mum, with a dark-count rate that can be as low as 10 -4 s -1 . The SSPD structures integrated with lambda/4 microcavities achieve a QE of 60% at telecommunication, 1550-nm wavelength. We have also developed a new generation of SSPDs that possess the QE of large-active-area devices, but, simultaneously, are characterized by low kinetic inductance that allows achieving short response times and the GHz-counting rate with picosecond timing jitter. The improvements presented in the SSPD development, such as fiber-coupled SSPDs, make our detectors most attractive for high-speed quantum communications and quantum computing. |
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1051-8223 |
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431 |
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Baselmans, J. J. A.; Hajenius, M.; Gao, J. R.; Baryshev, A.; Kooi, J.; Klapwijk, T. M.; Voronov, B.; de Korte, P.; Gol'tsman, G. |
Title |
NbN hot electron bolometer mixers: sensitivity, LO power, direct detection and stability |
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Journal Article |
Year |
2005 |
Publication |
IEEE Trans. Appl. Supercond. |
Abbreviated Journal |
IEEE Trans. Appl. Supercond. |
Volume |
15 |
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2 |
Pages |
484-489 |
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HEB mixers, direct detection effect, stability, Allan variance |
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We demonstrate that the performance of NbN lattice cooled hot electron bolometer mixers depends strongly on the interface quality between the bolometer and the contact structure. Both the receiver noise temperature and the gain bandwidth can be improved by a factor of 2 by cleaning the interface and adding an additional superconducting interlayer to the contact pad. Using this we obtain a double sideband receiver noise temperature of 950 K at 2.5 THz and 4.3 K, using a 0.4/spl times/4 /spl mu/m HEB mixer with a spiral antenna. At the same bias point, we obtain an IF gain bandwidth of 6 GHz. To comply with current demands on THz mixers for use in space based receivers we reduce the device size to 0.15/spl times/1 /spl mu/m and use a twin slot antenna. We report measurements of the noise temperature, LO power requirement, stability and the direct detection effect, using a mixer with a 1.6 THz twin slot antenna and a 1.462 THz solid state LO source with calibrated output power. |
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546 |
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Schwaab, G.W.; Sirmain, G.; Schubert, J.; Hubers, H.-W.; Gol'tsman, G.; Cherednichenko, S.; Verevkin, A.; Voronov, B.; Gershenzon, E. |
Title |
Investigation of NbN phonon-cooled HEB mixers at 2.5 THz |
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Journal Article |
Year |
1999 |
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IEEE Trans. Appl. Supercond. |
Abbreviated Journal |
IEEE Trans. Appl. Supercond. |
Volume |
9 |
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2 |
Pages |
4233-4236 |
Keywords |
NbN HEB mixers |
Abstract |
The development of superconducting hot electron bolometric (HEB) mixers has been a big step forward in the direction of quantum noise limited mixer performance at THz frequencies. Such mixers are crucial for the upcoming generation of airborne and spaceborne THz heterodyne receivers. In this paper we report on new results on a phonon-cooled NbN HEB mixer using e-beam lithography. The superconducting film is 3 nm thick. The mixer is 0.2 μm long and 1.5 μm wide and it is integrated in a spiral antenna on a Si substrate. The device is quasi-optically coupled through a Si lens and a dielectric beam combiner to the radiation of an optically pumped FIR ring gas laser cavity. The performance of the mixer at different THz frequencies from 0.69 to 2.55 THz with an emphasis on 2.52 THz is demonstrated. At 2.52 THz minimum DSB noise temperatures of 4200 K have been achieved at an IF of 1.5 GHz and a bandwidth of 40 MHz with the mixer mounted in a cryostat and a 0.8 m long signal path in air. |
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550 |
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Hajenius, M.; Barends, R.; Gao, J. R.; Klapwijk, T. M.; Baselmans, J. J. A.; Baryshev, A.; Voronov, B.; Gol'tsman, G. |
Title |
Local resistivity and the current-voltage characteristics of hot electron bolometer mixers |
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Journal Article |
Year |
2005 |
Publication |
IEEE Trans. Appl. Supercond. |
Abbreviated Journal |
IEEE Trans. Appl. Supercond. |
Volume |
15 |
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2 |
Pages |
495-498 |
Keywords |
HEB mixer distributed model, HEB distributed model, distributed HEB model |
Abstract |
Hot-electron bolometer devices, used successfully in low noise heterodyne mixing at frequencies up to 2.5 THz, have been analyzed. A distributed temperature numerical model of the NbN bridge, based on a local electron and a phonon temperature, is used to model pumped IV curves and understand the physical conditions during the mixing process. We argue that the mixing is predominantly due to the strongly temperature dependent local resistivity of the NbN. Experimentally we identify the origins of different transition temperatures in a real HEB device, suggesting the importance of the intrinsic resistive transition of the superconducting bridge in the modeling. |
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1051-8223 |
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980 |
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Author |
Gershenzon, E. M.; Gol'tsman, G. N.; Multanovskii, V. V.; Ptitsina, N. G. |
Title |
Kinetics of electron and hole binding into excitons in germanium |
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Journal Article |
Year |
1983 |
Publication |
Sov. Phys. JETP |
Abbreviated Journal |
Sov. Phys. JETP |
Volume |
57 |
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2 |
Pages |
369-376 |
Keywords |
Ge, electron and hole binding |
Abstract |
The kinetics of binding of free carriers'into excitons under stationary and nonstationary conditions is studied by investigating the submillimeter photoconductivity of Ge in a wide range of temperatures and of excitation levels. It is shown that the absolute values and the temperature dependence of the binding cross section (o- T-'.' ) can be satisfactorily described by the cascade recombination theory. The value of o and its temperature dependence differ significantly from the cross sections, measured in the same manner, for capture by attracting small impurities. Under nonstationary conditions, just as in the case of recombination with shallow impurities, a signifi- cant role is played by the sticking of the carriers in highly excited states. |
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1711 |
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