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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Gershenzon, E. M.; Gol'tsman, G. N.; Ptitsina, N. G.; Riger, E. R. |
Title |
Effect of electron-electron collisions on the trapping of free carriers by shallow impurity centers in germanium |
Type |
Journal Article |
Year |
1986 |
Publication |
Sov. Phys. JETP |
Abbreviated Journal |
Sov. Phys. JETP |
Volume |
64 |
Issue |
4 |
Pages |
889-897 |
Keywords |
Ge, trapping of free carriers |
Abstract |
Cascade Auger recombination of free carriers on shallow impurities in Ge is investigated under quasi-equilibrium conditions (T= 2-12 K) and in impurity breakdown. The Auger capture cross sections are found to be a,= 5. 10-l9 T-'n cm2 for donors and uip= 7- T-5p cm2 for acceptors. It is shown that in an isotropic semiconductor (p-Ge) ui is well described by the cascade-capture theory that takes into account only electron-electron collisions. In an anisotropic semiconductor ui is considerably larger (n-Ge, strongly uniaxially compressedp-Ge). Under impurity breakdown conditions the electron-electron collisions determine the lifetimes of the free carriers only in samples with appreciable density of the compensating impurity (Nk loi3 cmP3). |
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1707 |
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Lindgren, M.; Zorin, M. A.; Trifonov, V.; Danerud, M.; Winkler, D.; Karasik, B. S.; Gol'tsman, G. N.; Gershenzon, E. M. |
Title |
Optical mixing in a patterned YBa2Cu3O7-δ thin film |
Type |
Journal Article |
Year |
1994 |
Publication |
Appl. Phys. Lett. |
Abbreviated Journal |
Appl. Phys. Lett. |
Volume |
65 |
Issue |
26 |
Pages |
3398-3400 |
Keywords |
YBCO HTS HEB mixer, bandwidth |
Abstract |
Mixing of 1.56 µm infrared radiation from two lasers in a high quality YBa2Cu3O7-δ thin film, patterned to parallel strips, was demonstrated. A mixer bandwidth of 18 GHz, limited by the measurement system, was obtained. A model based on nonequilibrium electron heating gives a good fit to the data and predicts an intrinsic mixer bandwidth in excess of 100 GHz, operating in the whole infrared spectrum. Reduction of bolometric effects and ways to decrease the conversion loss of the mixer is discussed. The minimum conversion loss is expected to be ~10 dB. |
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0003-6951 |
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251 |
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Gol'tsman, G. N.; Gusinskii, E. N.; Malyavkin, A. V.; Ptitsina, N. G.; Selevko, A. G.; Edel'shtein, V. M. |
Title |
The excitonic Zeeman effect in uniaxially-strained germanium |
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Journal Article |
Year |
1987 |
Publication |
Sov. Phys. JETP |
Abbreviated Journal |
Sov. Phys. JETP |
Volume |
65 |
Issue |
6 |
Pages |
1233-1241 |
Keywords |
Ge, Zeeman effect |
Abstract |
We have carried out a high-resolution spectroscopic study of the absorption of submillimeter radiation by free excitons in germanium compressed along the [ 1 11 ] axis in a magnetic field parallel to the compression axis. In particular, we studied the splitting of the 1s- 2p transition in fields up to 6 kOe at T = 1.6 K, and observed a complex pattern in the Zeeman splitting which we believe is related to the effect of thermal motion of the excitons in a magnetic field on their internal structure (the magneto-Stark effect). The calculated submillimeter spectrum of excitons agrees with the experimental data. We predict that in a magnetic field the energy of the 2p, term is a minimum at a finite value of the exciton momentum perpendicular to the field-that is, the energy minimum forms a ring in momentum space. It follows that the density of states for this term must be a nonmonotonic function of the energy. A theory is developed of analogous phenomena in positronium. |
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1705 |
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Ekstörm, H.; Kollberg, E.; Yagoubov, P.; Gol'tsman, G.; Gershenzon, E.; Yngvesson, S. |
Title |
Gain and noise bandwidth of NbN hot-electron bolometric mixers |
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Journal Article |
Year |
1997 |
Publication |
Appl. Phys. Lett. |
Abbreviated Journal |
Appl. Phys. Lett. |
Volume |
70 |
Issue |
24 |
Pages |
3296-3298 |
Keywords |
NbN HEB mixers, conversion loss, conversion gain, U-factor technique |
Abstract |
We have measured the noise performance and gain bandwidth of 35 Å thin NbN hot-electron mixers integrated with spiral antennas on silicon substrate lenses at 620 GHz. The best double-sideband receiver noise temperature is less than 1300 K with a 3 dB bandwidth of ≈5 GHz. The gain bandwidth is 3.2 GHz. The mixer output noise dominated by thermal fluctuations is 50 K, and the intrinsic conversion gain is about −12 dB. Without mismatch losses and excluding the loss from the beamsplitter, we expect to achieve a receiver noise temperature of less than 700 K. |
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279 |
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