Records |
Author |
Zorin, M.; Lindgren, M.; Danerud, M.; Karasik, B.; Winkler, D.; Gol'tsman, G.; Gershenzon, E. |
Title |
Nonequilibrium and bolometric responses of YBaCuO thin films to high-frequency modulated laser radiation |
Type |
Journal Article |
Year ![sorted by Year field, ascending order (up)](img/sort_asc.gif) |
1995 |
Publication |
J. Supercond. |
Abbreviated Journal |
J. Supercond. |
Volume |
8 |
Issue |
1 |
Pages |
11-15 |
Keywords |
YBCO HTS HEB |
Abstract |
Picosecond nonequilibrium and slow bolometric responses to infrared radiation from a patterned high-T c superconducting (HTS) film in resistive and normal states deposited onto LaAlO3, NdGaO3, and MgO substrates were investigated using both pulse and modulation techniques. The response time of 35 ps to a laser pulse of 17 ps FWHM has been observed. The intrinsic response time of the fast process is expected to be about a few picoseconds. The modulation technique, being free from the disadvantages of pulse methods (poor sensitivity, limited dynamic range), makes the detailed study of a number of relaxation processes possible. Besides the nonequilibrium response, two kinds of bolometric processes, namely phonon transport through the film-substrate interface and phonon thermal diffusion in a substrate, manifest themselves in certain frequency dependences. |
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0896-1107 |
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Serial |
1630 |
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Author |
Yagubov, P.; Gol'tsman, G.; Voronov, B.; Seidman, L.; Siomash, V.; Cherednichenko, S.; Gershenzon, E. |
Title |
The bandwidth of HEB mixers employing ultrathin NbN films on sapphire substrate |
Type |
Conference Article |
Year ![sorted by Year field, ascending order (up)](img/sort_asc.gif) |
1996 |
Publication |
Proc. 7th Int. Symp. Space Terahertz Technol. |
Abbreviated Journal |
Proc. 7th Int. Symp. Space Terahertz Technol. |
Volume |
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Issue |
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Pages |
290-302 |
Keywords |
NbN HEB mixers, fabrication process |
Abstract |
We report on some unusual features observed during fabrication of ultrathin NbN films with high Tc. The films were used to fabricate HEB mixers, which were evaluated for IF bandwidth measurements at 140 GHz. Ultrathin films were fabricated using reactive dc magnetron sputtering with a discharge current source. Reproducible parameters of the films are assured keeping constant the difference between the discharge voltage in pure argon, and in a gas mixture, for the same current. A maximum bandwidth of 4 GHz at optimal LO and dc bias was obtained for mixer chip based on NbN film 35 A thick with Tc = 11 K. |
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Charlottesville, Virginia, USA |
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no |
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266 |
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Author |
Kawamura, J.; Blundell, R.; Tong, C.-Y. E.; Golts'man, G.; Gershenzon, E.; Voronov B. |
Title |
Superconductive NbN hot-electron bolometric mixer performance at 250 GHz |
Type |
Conference Article |
Year ![sorted by Year field, ascending order (up)](img/sort_asc.gif) |
1996 |
Publication |
Proc. 7th Int. Symp. Space Terahertz Technol. |
Abbreviated Journal |
Proc. 7th Int. Symp. Space Terahertz Technol. |
Volume |
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Issue |
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Pages |
331-336 |
Keywords |
NbN HEB mixers |
Abstract |
Thin film NbN (<40 A) strips are used as waveguide mixer elements. The electron cooling mechanism for the geometry is the electron-phonon interaction. We report a receiver noise temperature of 750 K at 244 GHz, with / IF = 1.5 GHz, Af= 500 MHz, and Tphysical = 4 K. The instantaneous bandwidth for this mixer is 1.6 GHz. The local oscillator (LO) power is 0.5 1.tW with 3 dB-uncertainty. The mixer is linear to 1 dB up to an input power level 6 dB below the LO power. We report the first detection of a molecular line emission using this class of mixer, and that the receiver noise temperature determined from Y-factor measurements reflects the true heterodyne sensitivity. |
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945 |
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Author |
Ekström, H.; Kroug, M.; Belitsky, V.; Kollberg, E.; Olsson, H.; Goltsman, G.; Gershenzon, E.; Yagoubov, P.; Voronov, B.; Yngvesson, S. |
Title |
Hot electron mixers for THz applications |
Type |
Conference Article |
Year ![sorted by Year field, ascending order (up)](img/sort_asc.gif) |
1996 |
Publication |
Proc. 30th ESLAB |
Abbreviated Journal |
Proc. 30th ESLAB |
Volume |
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Issue |
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Pages |
207-210 |
Keywords |
NbN HEB mixers |
Abstract |
We have measured the noise performance of 35 A thin NbN HEB devices integrated with spiral antennas on antireflection coated silicon substrate lenses at 620 GHz. From the noise measurements we have determined a total conversion gain of the receiver of—16 dB, and an intrinsic conversion of about-10 dB. The IF bandwidth of the 35 A thick NbN devices is at least 3 GHz. The DSB receiver noise temperature is less than 1450 K. Without mismatch losses, which is possible to obtain with a shorter device, and with reduced loss from the beamsplitter, we expect to achieve a DSB receiver noise temperature of less ‘than 700 K. |
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Noordwijk, Netherlands |
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Editor |
Rolfe, E. J.; Pilbratt, G. |
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Submillimetre and Far-Infrared Space Instrumentation |
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no |
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Serial |
1606 |
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Author |
Kawamura, J.; Blundell, R.; Tong, C.‐yu E.; Gol’tsman, G.; Gershenzon, E.; Voronov, B. |
Title |
Performance of NbN lattice‐cooled hot‐electron bolometric mixers |
Type |
Journal Article |
Year ![sorted by Year field, ascending order (up)](img/sort_asc.gif) |
1996 |
Publication |
J. Appl. Phys. |
Abbreviated Journal |
J. Appl. Phys. |
Volume |
80 |
Issue |
7 |
Pages |
4232-4234 |
Keywords |
NbN HEB mixers |
Abstract |
The heterodyne performance of lattice‐cooled hot‐electron bolometric mixers is measured at 200 GHz. Superconducting thin‐film niobium nitride strips with ∼5 nm thickness are used as waveguide mixer elements. A double‐sideband receiver noise temperature of 750 K at 244 GHz is measured at an intermediate frequency centered at 1.5 GHz with 500 MHz bandwidth and with 4.2 K device temperature. The instantaneous bandwidth for this mixer is 1.6 GHz. The local oscillator power required by the mixer is about 0.5 μW. The mixer is linear to within 1 dB up to an input power level 6 dB below the local oscillator power. A receiver incorporating a hot‐electron bolometric mixer was used to detect molecular line emission in a laboratory gascell. This experiment unambiguously confirms that the receiver noise temperature determined from Y‐factor measurements reflects the true heterodyne sensitivity. |
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0021-8979 |
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no |
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Serial |
1607 |
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Author |
Verevkin, A. A.; Ptitsina, N. G.; Smirnov, K. V.; Gol’tsman, G. N.; Gershenzon, E. M.; Ingvesson, K. S. |
Title |
Direct measurements of energy relaxation times on an AlGaAs/GaAs heterointerface in the range 4.2–50 K |
Type |
Journal Article |
Year ![sorted by Year field, ascending order (up)](img/sort_asc.gif) |
1996 |
Publication |
JETP Lett. |
Abbreviated Journal |
JETP Lett. |
Volume |
64 |
Issue |
5 |
Pages |
404-409 |
Keywords |
2DEG, AlGaAs/GaAs heterostructures |
Abstract |
The temperature dependence of the energy relaxation time τe (T) of a two-dimensional electron gas at an AlGaAs/GaAs heterointerface is measured under quasiequilibrium conditions in the region of the transition from scattering by acoustic phonons to scattering with the participation of optical phonons. The temperature interval of constant τe, where scattering by the deformation potential predominates, is determined. In the preceding, low-temperature region, where piezoacoustic and deformation-potential-induced scattering processes coexist, τ e decreases slowly with increasing temperature. Optical phonons start to participate in the scattering processes at T∼25 K (the characteristic phonon lifetime was equal to τLOτ4.5 ps). The energy losses calculated from the τe data in a model with an effective nonequilibrium electron temperature agree with the published data obtained under strong heating conditions. |
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0021-3640 |
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http://jetpletters.ru/ps/981/article_14955.shtml (“Прямые измерения времен энергетической релаксации на гетерогранице AlGaAs/GaAs в диапазоне 4.2 – 50 К”) |
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1608 |
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Author |
Verevkin, A. A.; Ptitsina, N. G.; Chulcova, G. M.; Gol'tsman, G. N.; Gershenzon, E. M.; Yngvesson, K. S. |
Title |
Direct measurements of energy relaxation time of electrons in AlGaAs/GaAs heterostructures under quasi-equilibrium conditions |
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Journal Article |
Year ![sorted by Year field, ascending order (up)](img/sort_asc.gif) |
1996 |
Publication |
Surface Science |
Abbreviated Journal |
Surface Science |
Volume |
361-362 |
Issue |
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Pages |
569-573 |
Keywords |
2DEG, AlGaAs/GaAs heterostructures |
Abstract |
For the first time, results are presented of a direct measurement of the energy relaxation time τε of 2D electrons in an AlGaAs/GaAs heterojunction at T = 1 and 5–20 K. A weak temperature dependence of τε for the T > 4K range and a linear temperature dependence of the reciprocal of τε for T < 4K have been observed. The linear dependence τε−1 ≈ T in the Bloch-Gruneisen regime is direct evidence of the predominance of the piezo-electric mechanism of electron-phonon interaction in non-elastic electron scattering processes. The values of τε in this regime are in very good agreement with the results of the Karpus theory. At higher temperatures, where the deformation-potential scattering becomes noticeable, a substantial disagreement between the experimental data and the theoretical results is observed. |
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0039-6028 |
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1609 |
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Author |
Semenov, A. D.; Gousev, Y. P.; Nebosis, R. S.; Renk, K. F.; Yagoubov, P.; Voronov, B. M.; Gol’tsman, G. N.; Syomash, V. D.; Gershenzon, E. M. |
Title |
Heterodyne detection of THz radiation with a superconducting hot‐electron bolometer mixer |
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Journal Article |
Year ![sorted by Year field, ascending order (up)](img/sort_asc.gif) |
1996 |
Publication |
Appl. Phys. Lett. |
Abbreviated Journal |
Appl. Phys. Lett. |
Volume |
69 |
Issue |
2 |
Pages |
260-262 |
Keywords |
NbN HEB mixers |
Abstract |
We report on the use of a superconducting hot‐electron bolometer mixer for heterodyne detection of terahertz radiation. Radiation with a wavelength of 119 μm was coupled to the mixer, a NbN microbridge, by a hybrid quasioptical antenna consisting of an extended hyperhemispherical lens and a planar logarithmic spiral antenna. We found, at an intermediate frequency of 1.5 GHz, a system double side band noise temperature of ≊40 000 K and conversion losses of 25 dB. We also discuss the possibilities of further improvement of the mixer performance. |
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0003-6951 |
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1610 |
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Boyarskii, D. A.; Gershenzon, V. E.; Gershenzon, E. M.; Gol'tsman, G. N.; Ptitsina, N. G.; Tikhonov, V. V.; Chulkova, G. M. |
Title |
On the possibility of determining the microstructural parameters of an oil-bearing layer from radiophysical measurement data |
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Journal Article |
Year ![sorted by Year field, ascending order (up)](img/sort_asc.gif) |
1996 |
Publication |
J. of Communications Technology and Electronics |
Abbreviated Journal |
J. of Communications Technology and Electronics |
Volume |
41 |
Issue |
5 |
Pages |
408-414 |
Keywords |
submillimeter waves, transmission |
Abstract |
A method for the reconstruction of microstructural properties of an oil-bearing rock from the spectral dependence of the transmission factor of submillimeter waves is proposed. |
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1064-2269 |
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Радиотехника и электроника 41, no. 4 (1996): 441-447 |
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no |
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1611 |
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Author |
Verevkin, A. A.; Ptitsina, N. G.; Chulcova, G. M.; Gol'Tsman, G. N.; Gershenzon, E. M.; Yngvesson, K. S. |
Title |
Determination of the limiting mobility of a two-dimensional electron gas in AlxGa1-xAs/GaAs heterostructures and direct measurement of the energy relaxation time |
Type |
Journal Article |
Year ![sorted by Year field, ascending order (up)](img/sort_asc.gif) |
1996 |
Publication |
Phys. Rev. B Condens. Matter. |
Abbreviated Journal |
Phys. Rev. B Condens. Matter. |
Volume |
53 |
Issue |
12 |
Pages |
R7592-R7595 |
Keywords |
2DEG, AlGaAs/GaAs heterostructures |
Abstract |
We present results for a method to measure directly the energy relaxation time (τe) for electrons in a single AlxGa1−xAs/GaAs heterojunction; measurements were performed from 1.6 to 15 K under quasiequilibrium conditions. We find τeαT−1 below 4 K, and τe independent of T above 4 K. We have also measured the energy-loss rate, ⟨Q⟩, by the Shubnikov-de Haas technique, and find ⟨Q⟩α(T3e−T3) for T<~4.2 K; Te is the electron temperature. The values and temperature dependence of τe and ⟨Q⟩ for T<4 K agree with calculations based on piezoelectric and deformation potential acoustic phonon scattering. At 4.2 K, we can also estimate the momentum relaxation time, τm, from our measured τe. This leads to a preliminary estimate of the phonon-limited mobility at 4.2 K of μ=3×107 cm2/Vs (ns=4.2×1011 cm−2), which agrees well with published numerical calculations, as well as with an earlier indirect estimate based on measurements on a sample with much higher mobility. |
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0163-1829 |
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PMID:9982274 |
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no |
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1612 |
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