Records |
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 |
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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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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0039-6028 |
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1609 |
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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 |
Type |
Journal Article |
Year |
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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1611 |
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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 |
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Journal Article |
Year |
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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1612 |
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Il'in, K. S.; Karasik, B. S.; Ptitsina, N. G.; Sergeev, A. V.; Gol'tsman, G. N.; Gershenzon, E. M.; Pechen, E. V.; Krasnosvobodtsev, S. I. |
Title |
Electron-phonon-impurity interference in thin NbC films: electron inelastic scattering time and corrections to resistivity |
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Conference Article |
Year |
1996 |
Publication |
Czech. J. Phys. |
Abbreviated Journal |
Czech. J. Phys. |
Volume |
46 |
Issue |
S2 |
Pages |
857-858 |
Keywords |
NbC films |
Abstract |
Complex study of transport properties of impure NbC films with the electron mean free pathl=0.6–13 nm show the crucial role of the electron-phonon-impurity interference (EPII). In the temperature range 20–70 K we found the interference correction to resistivity proportional to T2 and to the residual resistivity of the film. Using the comprehensive theory of EPII, we determine the electron coupling with transverse phonons and calculate the electron inelastic scattering time. Direct measurements of the inelastic electron scattering time using a response to a high-frequency amplitude modulated cw radiation agree well with the theory. |
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0011-4626 |
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no |
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1617 |
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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 |
Type |
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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Varyukhin, S. V.; Zakharov, A. A.; Gershenzon, E. M.; Gol'tsman, G. N.; Ptitsina, N. G.; Chulkova, G. M. |
Title |
Low energy excitation in La2CuO4 |
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Journal Article |
Year |
1990 |
Publication |
Sverkhprovodimost': Fizika, Khimiya, Tekhnika |
Abbreviated Journal |
Sverkhprovodimost': Fizika, Khimiya, Tekhnika |
Volume |
3 |
Issue |
5 |
Pages |
832-837 |
Keywords |
metal-dielectric-La2CuO4, monocrystals |
Abstract |
Measurements of transmission and photoconductivity spectra in submillimeter wave length range as well as of capacity C and conductivity G in the region of acoustic frequencies of metal-dielectric-La2CuO4 system at low temperatures are performed using La2CuO4 monocrystals. Optical spectra posses a threshold character, a sharp decrease of transmission and photocoductivity signal occurs in the energy region hν>1.5 MeV. C(ω,T) and G(ω, T) dependences have a universal form typical of Debye type relaxation processes. Relaxation time dependence is of thermoactivated character τ(T)∼exp(ξ/T) with the gap value ξ≅2 meV. It is assumed that excitations with characteristic energy of ∼2 meV exist in La2CuO4. A possible nature of the detected low-energy excitations is discussed. |
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1688 |
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Voevodin, E. I.; Gershenzon, E. M.; Goltsman, G. N.; Ptitsina, N. G. |
Title |
Energy-spectrum of shallow acceptors in Ge deformed strongly by a uniaxial pressure |
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Journal Article |
Year |
1989 |
Publication |
Sov. Phys. and Technics of Semiconductors |
Abbreviated Journal |
Sov. Phys. and Technics of Semiconductors |
Volume |
23 |
Issue |
8 |
Pages |
843-846 |
Keywords |
Ge, crystallography |
Abstract |
Проведены исследования спектров фототермической ионизации мелких акцепторов (В, Аl) в Ge, предельно сжатом вдоль кристаллографической оси [100]. Из данных измерений с учетом теории построен энергетический спектр примесей. Показано, что энергии большого числа уровней четных и нечетных состояний хорошо соответствуют расчету, выполненному для примесей в анизотропном полупроводнике с параметром анизотропии γ=m∗⊥/m∗∥>1. |
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Энергетический спектр мелких акцепторов в сильно одноосно деформированном Ge |
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1692 |
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Voevodin, E. I.; Gershenzon, E. M.; Goltsman, G. N.; Ptitsina, N. G.; Chulkova, G. M. |
Title |
Capture of free holes by charged acceptors in uniaxially deformed Ge |
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Journal Article |
Year |
1988 |
Publication |
Fizika i Tekhnika Poluprovodnikov |
Abbreviated Journal |
Fizika i Tekhnika Poluprovodnikov |
Volume |
22 |
Issue |
3 |
Pages |
540-543 |
Keywords |
Ge, free holes, capture |
Abstract |
Цель настоящей работы — исследование кинетики примесной фотопроводимости p-Ge при сильном одноосном сжатии в широком диапазоне изменения интенсивности примесного подсвета, создающего свободные дырки, и определение сечения каскадного захвата дырок на мелкие заряженные акцепторы в условиях преобладания электрон-фононного механизма потерь энергии. |
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Russian |
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Захват свободных дырок заряженными акцепторами в одноосно деформированном Ge |
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1698 |
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Gershenzon, Ye. M.; Goltsman, G. N.; Yelantyev, A. I.; Petrova, Ye. B.; Ptitsina, N. G.; Filatov, V. S. |
Title |
Lecture demonstrations of properties of superconductors and liquid helium |
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Journal Article |
Year |
1987 |
Publication |
USSR Rept Phys. Math. JPRS UPM |
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USSR Rept Phys. Math. JPRS UPM |
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24 |
Issue |
7 |
Pages |
51 |
Keywords |
demonstrations, lections |
Abstract |
New demonstrations for low temperature physics courses are described. Two transparent Dewar vacuum flasks fitting one inside the other with the external flask for nitrogen and the internal flask for helium are used. The helium temperature can be regulated in the 4.2 to 1.6 K range and the effects of reducing helium to the superfluid state at 2.17 K can be shown: boiling abruptly stops and superfluid flow appears. In order to show the electric and magnetic characteristics of superconductivity, a superconducting NbTi solenoid containing nonsuperconducting wire and germanium and superconducting Nb materials with different critical temperatures is placed in the helium refrigerant vessel. The fall of the resistance at the critical temperatures can be shown. In order to show magnetic field and superconductive current flow properties a shunt of superconductive material is connected in parallel to the coil and is enclosed in a teflon container with a heater which can vary its temperature. When it is heated and not superconductive, magnetic field effects can be demonstrated and when it is unheated and superconducting a continuous current can be demonstrated. |
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1704 |
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