| Records |
| Author |
Verevkin, A. I.; Ptitsina, N. G.; Chulkova, G. M.; Gol'tsman, G. N.; Gershenzon, E. M.; Yngvesson, K. S. |
| Title |
Electron energy relaxation in a 2D channel in AlGaAs-GaAs heterostructures under quasiequilibrium conditions at low temperatures |
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Journal Article |
| Year |
1995 |
Publication |
JETP Lett. |
Abbreviated Journal |
JETP Lett. |
| Volume |
61 |
Issue |
7 |
Pages |
591-595 |
| Keywords |
2DEG, AlGaAs/GaAs heterostructures |
| Abstract |
The energy relaxation time of 2D electrons, Te, has been measured under quasiequilibrium conditions in AlGaAs—GaAs heterojunctions over the temperature range T= 1.5—20 K. At T> 4 K, Te depends only weakly on the temperature, while at T< 4 K 7;'(T) there is a dependence fr; lNT. A linear dependence 7: 1 (T) in the Bloch—-Grfineisen temperature region (T< 5 K) is unambiguous evidence that a piezoacoustic mechanism of an electron—phonon interaction is predominant in the inelastic scattering of electrons. The values of T6 in this temperature range agree very accurately with theoretical results reported by Karpus [Sov. Phys. Semicond. 22 (1988)]. At higher temperatures, where scat—tering by deformation acoustic phonons becomes substantial, there is a significant discrepancy between the experimental and theoretical re-sults. |
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1624 |
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Zorin, M.; Lindgren, M.; Danerud, M.; Karasik, B.; Winkler, D.; Gol'tsman, G.; Gershenzon, E. |
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Nonequilibrium and bolometric responses of YBaCuO thin films to high-frequency modulated laser radiation |
Type |
Journal Article |
| Year |
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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1630 |
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Karasik, B. S.; Elantiev, A. I. |
| Title |
Analysis of the noise performance of a hot-electron superconducting bolometer mixer |
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Conference Article |
| Year |
1995 |
Publication |
Proc. 6th Int. Symp. Space Terahertz Technol. |
Abbreviated Journal |
Proc. 6th Int. Symp. Space Terahertz Technol. |
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Pages |
229-246 |
| Keywords |
HEB mixers |
| Abstract |
A theoretical analysis for the noise temperature of hot–electron superconducting mixer has been presented. Thecontributions of both Johnson noise and electron temperature fluctuations have been evaluated. A set of criteriaensuring low noise performance of the mixer has been stated and a simple analytic expression for the noisetemperature of the mixer device has been suggested. It has been shown that an improvement of the mixer sensitivitydoes not necessarily follow by a decrease of the bandwidth. An SSB noise temperature limit due to the intrinsic noisemechanisms has been estimated to be as low as 40–90 K for a mixer device made from Nb or NbN thin film.Furthermore, the conversion gain bandwidth can be as wide as is allowed by the intrinsic electron temperaturerelaxation time if an appropriate choice of the mixer resistance has been made. The intrinsic mixer noise bandwidthis of 3 GHz for Nb device and of 5 GHz for NbN device. An additional improvement of the theory has been madewhen a distinction between the impedance measured at high intermediate frequency (larger than the mixerbandwidth) and the mixer ohmic resistance has been taken into account.Recently obtained experimental data on Nb and NbNbolometer mixer devices are viewed in connection with thetheoretical predictions.The noise temperature limit has also been specified for the mixer device where an outdiffusion coolingmechanism rather than the electron–phonon energy relaxation determines the mixer bandwidth. A consideration ofthe noise performance of a bolometer mixer made from YBaCuO film utilizing a hot–electron effect has been done. |
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Pasadena, Ca |
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258 |
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Hesler, J. L.; Crowe, T. W.; Bradley, R. F.; Pan, S. K.; Chattopadhyay, G. |
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The design, construction and evaluation of a 585 GHz planar Schottky mixer |
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Conference Article |
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1995 |
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Proc. 6th Int. Symp. Space Terahertz Technol. |
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34-43 |
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Pasadena, Ca |
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259 |
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Okunev, 0.; Dzardranov, A.; Gol'tsman, G.; Gershenzon, E. |
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Performances of hot—electron superconducting mixer for frequencies less than the gap energy: NbN mixer for 100 GHz operation |
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Conference Article |
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1995 |
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Proc. 6th Int. Symp. Space Terahertz Technol. |
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Proc. 6th Int. Symp. Space Terahertz Technol. |
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247-253 |
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NbN HEB mixers |
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The possibilities to improve the parameters of the 100 GHz NbN HEB superconducting waveguide mixers have been studied. The device consists of a signal strip 1 gm wide by 2 Am long made of 40 A thick NbN film. The best operation point was found at 5 K, where the mixer bandwidth made up 1.5-2 GHz and the total loss diminished down to 8 dB. The critical current density has been increased up to " 40 6 A/cm 2 , the noise temperature of the receiver (DSB) has reduced down to 450 K and the local oscillator power has decreased down to -.4).1 mcV. |
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1625 |
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