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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. |
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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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Gerecht, E.; Musante, C. F.; Schuch, R.; Lutz, C. R.; Jr.; Yngvesson, K. S.; Mueller, E. R.; Waldivian, J.; Gol'tsman, G. N.; Voronov, B. M.; Gershenzon, E. M. |
Title |
Hot electron detection and mixing experiments in NbN at 119 micrometer wavelength |
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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 |
284-293 |
Keywords |
NbN HEB mixers, detectors |
Abstract |
We have performed preliminary experiments with the goal of demonstrating a Hot Electron Bolometric (HEB) mixer for a 119 micrometer wavelength (2.5 THz). We have chosen a NbN device of size 700 x 350 micrometers. This device can easily be coupled to a laser LO source, which is advantageous for performing a prototype experiment. The relatively large size of the device means that the LO power required is in the mW range; this power can be easily obtained from a THz laser source. We have measured the amount of laser power actually absorbed in the device, and from this have estimated the best optical coupling loss to be about 10 di . We are developing methods for improving the optical coupling further. Preliminary measurements of the response of the device to a chopped black-body have not yet resulted in a measured receiver noise temperature. We expect to be able to complete this measurement in the near future. |
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1629 |
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Ekström, H.; Karasik, B.; Kollberg, E.; Yngvesson, K. S. |
Title |
Investigation of a superconducting hot electron mixer |
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Conference Article |
Year |
1994 |
Publication |
Proc. 5th Int. Symp. Space Terahertz Technol. |
Abbreviated Journal |
Proc. 5th Int. Symp. Space Terahertz Technol. |
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Pages |
169-188 |
Keywords |
HEB mixers |
Abstract |
Mixing at 20 GHz in niobium superconducting thin film strips in the resistive state is studied. Experiments give evidence that electron-heating is the main cause of the non linear phenomena. The requirements on the mode of operation and on the film parameters for small conversion loss and the possibility of conversion gain are discussed. Measurements indicate a minimum intrinsic conversion loss around 1 dB with a sharp drop for the lowest voltage bias-points, and a DSB mixer noise temperature between 100 and 450 K at 20 GHz. The device output noise temperature at the mixer operating point can be as low as 30-50 K. A simple theory is presented, which is based on the assumption that the small signal resistance is linearly dependent on power. This type of mixer is considered very promising for use in low-noise heterodyne receivers at THz frequencies. |
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1642 |
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Ekstrom, H.; Karasik, B.; Weikle, R.; Yngvesson, K. S.; Gol’tsman, G.; Kollberg, E.; Gershenzon, E. |
Title |
Mixers using superconducting Nb films in the resistive state |
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Conference Article |
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1993 |
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23rd European Microwave Conf. |
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23rd European Microwave Conf. |
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787-789 |
Keywords |
Nb HEB mixers |
Abstract |
The mixing of 20 GHz radiation in a Nb superconducting film in the resistive state was studied. The experiment gave evidence of electron-heating to be the origin of the non-linear phenomenon. The requirements on the operation mode and on the film parameters in order to obtain small conversion losses or even gain are determined. Our measurements indicate a conversion loss of about 6-8 dB. The hot-electron bolometer is considered to be very promising for use in heterodyne receivers in a wide frequency range from microwaves to terahertz frequencies. |
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1651 |
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