| Records |
| 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 |
Type |
Journal Article |
| Year |
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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| ISSN |
0039-6028 |
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1609 |
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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 |
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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1607 |
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Gousev, Yu. P.; Semenov, A. D.; Pechen, E. V.; Varlashkin, A. V.; Nebosis, R. S.; Renk K. F |
| Title |
Coupling of terahertz radiation to a high-Т(с) superconducting hot electron bolometer mixer |
Type |
Journal Article |
| Year |
1996 |
Publication |
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Abbreviated Journal |
Appl. Phys. Lett., |
| Volume |
69 |
Issue |
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Pages |
691-693 |
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| Abstract |
We report on efficient coupling of THz radiation to a high-T(c) superconducting hot electron bolometer that is suitable for heterodyne detection. Our quasioptical system consisted of a planar self-complementary spiral antenna on a dielectric substrate clamped to an extended hyperhemispherical lens. The antenna was integrated into a co-planar line for broadband intermediate frequency matching. Measurements in the homodyne regime at a frequency of 2.5 THz showed a radiation pattern with a beam width of 1° and a coupling efficiency of 0.1. We measured, at an intermediate frequency of 1.5 GHz, an output noise temperature of'160 K and estimated for the device, operated in the heterodyne regime, a system noise temperature of 30 000 K. We also discuss possibilities of significant improvement of the sensitivity. |
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RPLAB @ atomics90 @ |
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958 |
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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 |
Type |
Journal Article |
| Year |
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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| ISSN |
0003-6951 |
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no |
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Serial |
1610 |
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| Author |
Karasik, B. S.; Elantiev, A. I. |
| Title |
Noise temperature limit of a superconducting hot-electron bolometer mixer |
Type |
Journal Article |
| Year |
1996 |
Publication |
Applied Physics Letters |
Abbreviated Journal |
Appl. Phys. Lett. |
| Volume |
68 |
Issue |
6 |
Pages |
853-855 |
| Keywords |
HEB mixer noise temperature, Johnson noise, thermal fluctuation noise, noise bandwidth |
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0003-6951 |
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no |
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Serial |
260 |
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