| Records |
| Author |
Bell, M.; Sergeev, A.; Mitin, V.; Bird, J.; Verevkin, A.; Gol’tsman, G. |
| Title |
One-dimensional resistive states in quasi-two-dimensional superconductors: Experiment and theory |
Type |
Journal Article |
| Year |
2007 |
Publication |
Phys. Rev. B |
Abbreviated Journal |
Phys. Rev. B |
Volume  |
76 |
Issue |
9 |
Pages |
094521 (1 to 5) |
| Keywords |
uasi-two-dimensional superconductors, NbN |
| Abstract |
We investigate competition between one- and two-dimensional topological excitations—phase slips and vortices—in the formation of resistive states in quasi-two-dimensional superconductors in a wide temperature range below the mean-field transition temperature TC0. The widths w=100nm of our ultrathin NbN samples are substantially larger than the Ginzburg-Landau coherence length ξ=4nm, and the fluctuation resistivity above TC0 has a two-dimensional character. However, our data show that the resistivity below TC0 is produced by one-dimensional excitations—thermally activated phase slip strips (PSSs) overlapping the sample cross section. We also determine the scaling phase diagram, which shows that even in wider samples the PSS contribution dominates over vortices in a substantial region of current and/or temperature variations. Measuring the resistivity within 7 orders of magnitude, we find that the quantum phase slips can only be essential below this level. |
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| ISSN |
1098-0121 |
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1423 |
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| Author |
Danerud, M.; Winkler, D.; Lindgren, M.; Zorin, M.; Trifonov, V.; Karasik, B. S.; Gol’tsman, G. N.; Gershenzon, E. M. |
| 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 |
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. |
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0021-8979 |
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no |
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1637 |
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Shangina, E. L.; Smirnov, K. V.; Morozov, D. V.; Kovalyuk, V. V.; Gol’tsman, G. N.; Verevkin, A. A.; Toropov, A. I. |
| Title |
Concentration dependence of the intermediate frequency bandwidth of submillimeter heterodyne AlGaAs/GaAs nanostructures |
Type |
Journal Article |
| Year |
2010 |
Publication |
Bull. Russ. Acad. Sci. Phys. |
Abbreviated Journal |
Bull. Russ. Acad. Sci. Phys. |
| Volume |
74 |
Issue |
1 |
Pages |
100-102 |
| Keywords |
2DEG AlGaAs/GaAs heterostructures, THz heterodyne detectors, IF bandwidth |
| Abstract |
The concentration dependence of the intermediate frequency bandwidth of heterodyne AlGaAs/GaAs detectors with 2D electron gas is measured using submillimeter spectroscopy with high time resolution at T= 4.2 K. The intermediate frequency bandwidth f3dBfalls from 245 to 145 MHz with increasing concentration of 2D electrons n s = (1.6-6.6) × 10[su11] cm-2. The dependence f3dB ≈ n s – 0.04±is observed in the studied concentration range; this dependence is determined by electron scattering by the deformation potential of acoustic phonons and piezoelectric scattering. |
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1062-8738 |
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no |
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1217 |
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| Author |
Gol’tsman, G. N.; Smirnov, K. V. |
| Title |
Electron-phonon interaction in a two-dimensional electron gas of semiconductor heterostructures at low temperatures |
Type |
Journal Article |
| Year |
2001 |
Publication |
Jetp Lett. |
Abbreviated Journal |
Jetp Lett. |
| Volume |
74 |
Issue |
9 |
Pages |
474-479 |
| Keywords |
2DEG, AlGaAs/GaAs heterostructures |
| Abstract |
Theoretical and experimental works devoted to studying electron-phonon interaction in the two-dimensional electron gas of semiconductor heterostructures at low temperatures in the case of strong heating in an electric field under quasi-equilibrium conditions and in a quantizing magnetic field perpendicular to the 2D layer are considered. |
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0021-3640 |
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По итогам проектов российского фонда фундаментальных исследований. Проект РФФИ # 98-02-16897 Электрон-фононное взаимодействие в двумерном электронном газе полупроводниковых гетероструктур при низких температурах |
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1541 |
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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. |
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0003-6951 |
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no |
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1579 |
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