共查询到20条相似文献,搜索用时 31 毫秒
1.
R. Hattori K. Fujii T. Ohyama M. Isshiki 《Physica E: Low-dimensional Systems and Nanostructures》2006,32(1-2):237
Electronic properties of confined electrons at naturally formed twin boundaries in ZeSe have been investigated by microwave absorption measurements. Cyclotron resonance signal of the confined electrons was observed. On the cyclotron resonance peak, novel oscillation of the absorption intensity was observed. Similar oscillatory behavior was also observed in GaAs/AlGaAs heterostructures near cyclotron resonance filed at which new Shubnikov–de Haas-like oscillation was observed by Zudov. The oscillatory structure has a period not in inverse magnetic field but magnetic field. The origin of the oscillation observed is caused by Rayleigh interference of two-dimensional electron gas. 相似文献
2.
We have investigated optically detected cyclotron resonance (ODCR) and ordinary cyclotron resonance (CR) under the same condition, in Ge and Si, which include both high-purity and doped samples. In impact dissociation processes, which are the origin of ODCR, donorbound excitons have larger cross section for impinging electrons than for holes, and conversely, acceptor- bound excitons have larger cross section for holes than for electrons. Moreover, the ratio of impact dissociation cross section for holes to that for electrons varies with the number of excitons bound to an impurity. These phenomena are understood primarily in terms of exchange interaction between impinging carriers and constituents of bound excitons. In addition, it is found that the relative intensity of hole cyclotron resonance against electron resonance is larger in ODCR than in CR. This is understood in terms of exchange interaction by taking the many valley nature of the conduction band into account. 相似文献
3.
S. D. Suchalkin Yu. B. Vasil’ev K. von Klitzing V. N. Golovach G. G. Zegrya S. V. Ivanov P. S. Kop’ev B. Ya. Mel’tser 《JETP Letters》1998,68(10):792-798
The mechanism of oscillations of the half-width and intensity of the cyclotron resonance (CR) line of electrons in a semimetal
quantum well based on an InAs/AlSb/GaSb heterostructure is investigated experimentally and theoretically. It is shown that
the oscillations of the CR spectrum are due to mixing of states of the spatially separated two-dimensional electrons and holes.
Pis’ma Zh. éksp. Teor. Fiz. 68, No. 10, 753–758 (25 November 1998) 相似文献
4.
L. V. Kulik A. V. Gorbunov A. S. Zhuravlev V. B. Timofeev I. V. Kukushkin 《Journal of Experimental and Theoretical Physics》2016,122(3):525-530
An experimental technique is developed to perform photoexcitation of an ensemble of translationinvariant triplet excitons, to manipulate this ensemble, and to detect the properties of its components. In particular, the influence of temperature on the radiationless decay during the relaxation of an exciton spin into the ground state of a Hall insulator at a filling factor ν = 2 is studied. The generation of photoexcited electrons and holes is controlled using photoinduced resonance reflection spectra, which makes it possible to estimate the density of light-generated electron–hole pairs and to independently control the self-consistent generation of electrons at the first Landau level and holes (vacancies) at the ground (zero) cyclotron electronic level. The existence of triplet excitons is established from inelastic light scattering spectra, which are used to determine the singlet–triplet exciton splitting. The lifetimes of triplet excitons, which are closely related to the relaxation time of an electron spin, are extremely long: they reach 100 μs in perfect GaAs/AlGaAs heterostructures with a high mobility of two-dimensional electrons at low temperatures. These long spin relaxation times are qualitatively explained, and the expected collective behavior of high-density triplet magnetoexcitons at sufficiently low temperatures, which is related to their Bose nature, is discussed. 相似文献
5.
A. A. Greshnov G. G. Zegrya Yu. B. Vasil’ev S. D. Suchalkin B. Ya. Mel’tser S. V. Ivanov P. S. Kop’ev 《JETP Letters》2002,76(4):222-226
The mechanism of cyclotron resonance line splitting in the InAs/GaSb heterostructure in an inclined magnetic field has been studied experimentally and theoretically. It is shown that the admixing of electron and hole states leads to anticrossing of the Landau levels and, hence, to splitting of the cyclotron resonance line. In the case of an inclined magnetic field, the splitting is not observed, which is explained by the suppression of the admixing of electron and hole states due to the occurrence of an additional barrier for electrons and holes given a longitudinal magnetic field component. 相似文献
6.
Study of runaway electron behaviour during electron cyclotron resonance heating in the HL-2A Tokamak 下载免费PDF全文
During the current flat-top phase of electron cyclotron
resonance heating discharges in the HL-2A Tokamak, the behaviour of
runaway electrons has been studied by means of hard x-ray detectors
and neutron diagnostics. During electron cyclotron resonance
heating, it can be found that both hard x-ray radiation intensity
and neutron emission flux fall rapidly to a very low level, which
suggests that runaway electrons have been suppressed by electron
cyclotron resonance heating. From the set of discharges studied in
the present experiments, it has also been observed that the
efficiency of runaway suppression by electron cyclotron resonance
heating was apparently affected by two factors: electron cyclotron
resonance heating power and duration. These results have been
analysed by using a test particle model. The decrease of the
toroidal electric field due to electron cyclotron resonance heating
results in a rapid fall in the runaway electron energy that may lead
to a suppression of runaway electrons. During electron cyclotron
resonance heating with different powers and durations, the runaway
electrons will experience different slowing down processes. These
different decay processes are the major cause for influencing the
efficiency of runaway suppression. This result is related to the
safe operation of the Tokamak and may bring an effective control of
runaway electrons. 相似文献
7.
Z. D. Kvon D. A. Kozlov S. N. Danilov C. Zoth P. Vierling S. Stachel V. V. Bel’kov A. K. Bakarov D. V. Dmitriev A. I. Toropov S. D. Ganichev 《JETP Letters》2013,97(1):41-44
The terahertz response of a high-density and high-mobility two-dimensional electron gas in 13-nm GaAs quantum wells at frequencies of 0.7 and 1.63 THz has been investigated. Terahertz radiation-induced magnetoresistance oscillations have been discovered. The oscillation maxima coincide with the harmonics of cyclotron resonance. It has been shown that a large number of harmonics (up to the ninth) appear under irradiation at a frequency of 0.7 THz. In this case, the effect is the analogue of microwave-induced oscillations. At a higher frequency, the oscillation amplitude decreases drastically with an increase in the harmonic number. This indicates a transition to the regime of ordinary cyclotron harmonics. 相似文献
8.
The properties of plasma and magnetoplasma excitations in free-hanging graphene have been studied for the first time by Raman scattering. In addition to single-particle excitations associated with transitions between empty Landau levels of electrons and holes, collective plasma and magnetoplasma excitations in the system of electrons (and holes) of various densities have been discovered for the first time. Hybridization of plasma and cyclotron modes corresponding to the Kohn law has been shown to occur in the limit of high filling factors, which allows measuring directly the plasma and cyclotron energies. The dependence of the electron and hole velocities on their density has been investigated via the magnetic-field dependence of the cyclotron energy in free-hanging graphene. The effect of strong renormalization of the electron and hole dispersion relations seen as an increase in the velocity (by 40–50%) with a decrease in the charge-carrier density to 1011 cm–2 has been discovered. The charge-carrier density dependences of the widths of magnetoplasma resonances in free-hanging graphene and graphene lying on a silicon dioxide surface have been measured and shown to be at least 3.5 and 14.8 meV, respectively. 相似文献
9.
Nonlinear magnetotransport of two-dimensional electrons in square antidot lattices prepared on the basis of selectively doped GaAs/AlAs heterostructures with the period that is much less than the electron mean free path in the initial GaAs quantum wells but is much larger than their Fermi wavelength has been studied. It has been shown that the character of the nonlinear transport of the two-dimensional electrons in the lateral lattices under study changes from classical to quantum with the decrease in the antidot radius. It has been found that the quantum lifetime increases in the magnetic field corresponding to the condition of equality of the cyclotron diameter of two-dimensional electrons and the antidot lattice period. 相似文献
10.
M.I. Dykman 《Solid State Communications》1980,35(10):753-757
The cyclotron resonance peak shape is analysed for two-dimensional electrons interacting with surface vibrations of a medium. Explicit expressions for the broadening and shift of the peak are obtained at low and high electron densities. 相似文献
11.
The dispersion of magnetoplasma excitations in two-dimensional electron systems in a strong parallel magnetic field has been
studied. A considerable increase in the electron cyclotron mass with an increase in the parallel component of magnetic field
has been detected. It has been found that the cyclotron mass increment is a quadratic function of the magnetic field parallel
to the interface. It has been shown that the mass anisotropy of 2D electrons induced by the parallel magnetic field reaches
nearly 2.5 in B
‖ = 7 T. The energy of space quantization of the electron in the quantum well has been estimated from the magnetic field dependence
of the anisotropy. 相似文献
12.
We have observed cyclotron resonance in a high-mobility GaAs/AlGaAs two-dimensional electron gas by using the techniques of terahertz time-domain spectroscopy combined with magnetic fields. From this, we calculate the real and imaginary parts of the diagonal elements of the magnetoconductivity tensor, which in turn allows us to extract the concentration, effective mass, and scattering time of the electrons in the sample. We demonstrate the utility of ultrafast terahertz spectroscopy, which can recover the true linewidth of cyclotron resonance in a high-mobility (>10(6) cm(2)V(-1)s(-1)) sample without being affected by the saturation effect. 相似文献
13.
By means of high resolution optical lithography two-dimensional (2D) electron inversion layers in metal-oxide-semiconductor (MOS) structures on InSb are laterally confined to narrow channels. The widths of the channels (w≈100nm) are comparable to the de-Broglie wavelength of the electrons and formation of one-dimensional (1D) subbands results. This is verified by direct spectroscopy of intersubband transitions between the 1D subbands at far-infrared frequencies. Cyclotron resonance experiments also show the importance of the lateral confining potential. In particular, the transition from 1D to 2D electronic behavior is observed when the magnetic field strength is increased and the cyclotron radius ℓ becomes much less than the channel width w. 相似文献
14.
A. V. Ikonnikov A. A. Lastovkin K. E. Spirin M. S. Zholudev V. V. Rumyantsev K. V. Maremyanin A. V. Antonov V. Ya. Aleshkin V. I. Gavrilenko S. A. Dvoretskii N. N. Mikhailov Yu. G. Sadofyev N. Samal 《JETP Letters》2010,92(11):756-761
The energy spectra of quantum-well narrow-bandgap Hg1 ? y Cd y Te/Cd x Hg1 ? x Te heterostructures have been studied. The dependences of the effective cyclotron mass on the density (in classical magnetic fields) and the transition energy (in quantizing fields) have been obtained from the cyclotron resonance measurements. These dependences confirm the near-linear dispersion law for the electrons with small mass at the band bottom (the minimum cyclotron mass measured is 0.003 m 0). The interband photoconductivity of the CdHgTe-based structures with the long-wavelength photoresponse edge lower than 6 meV has been demonstrated. 相似文献
15.
An electrostatic model for calculating the band-gap renormalization in a two-dimensional (2D) semiconductor layer (quantum well) due to the Coulomb interaction between nonequilibrium charge carriers has been proposed. Consideration is given only to the first quantum-well energy levels for electrons and heavy holes. The exchange and correlation energies are calculated for the first time taking into account the charge-carrier potential energyfluctuations created by electrons and holes along the 2D layer. A relationship for the screened Coulomb potential along the 2D layer is derived, which, within the extremely narrow quantum-well approximation, transforms into the known expression. The band-gap renormalization and the photoluminescence line shape for the GaAs 2D layer in an AlxGa1?x As matrix are computed depending on the concentration of nonequilibrium electrons and holes. The calculated band-gap renormalization is in agreement with the available experimental data at a high photoexcitation of the quantum well when the electrons and holes form the 2D plasma. 相似文献
16.
M. N. Khannanov I. V. Kukushkin S. I. Gubarev J. Smet K. von Klitzing W. Wegscheider C. Gerl 《JETP Letters》2007,85(5):242-245
The dependence of the heavy-hole cyclotron mass in GaAs(001) quantum wells on the 2D-hole density has been measured by the optical detection method for resonance microwave by-absorption. A significant increase (almost doubling) has been observed in the cyclotron mass of heavy holes with an increase in the charge carrier density from 1.2 × 1010 cm?2 to 1.3 × 1011 cm?2. 相似文献
17.
é. G. Batyev 《Journal of Experimental and Theoretical Physics》2010,110(1):88-97
A system of two-dimensional electrons and holes ha s been investigated in a strong magnetic field, when it is sufficient to
take into account only the ground Landau level. It has been shown that the interaction of electrons and holes can lead to
an ordered state. In this problem, the exchange interaction in electron and hole subsystems is significant. The following
two cases have been considered: (a) there are one electron and one hole valleys, and at some magnetic field strength, there
exists an ordered state, as in an excitonic insulator; and (b) there exist one electron and two equivalent hole valleys (as
in the experiment performed by Kvon et al. [1]), and the hole system has an ordered state of the Stoner ferromagnetic type
in a specific range of magnetic field strengths. The spectra of elementary excitations of the Bose and Fermi types have been
obtained. The Fermi excitations have a gap in the energy spectrum, whereas the Bose excitations in the ordered states begin
with zero (to these excitations there corresponds an electric dipole moment). The self-consistent field approximation has
been used, which is exact when the numbers of electrons and holes are equal to each other. 相似文献
18.
A. Gold 《Zeitschrift für Physik B Condensed Matter》1986,63(1):1-8
A theory for static and dynamic transport of a two-dimensional electron gas in GaAs-AlGaAs heterostructures at temperature zero is presented. Charged impurities, separated from the electron gas by a spacer layer, are considered as the dominant scattering mechanism. Finite extension of the wave function of the two-dimensional electron gas is taken into account. Multiple scattering effects are included and are shown to lead to a metal insulator transition at low electron densities. Due to plasmon dynamics the scattering is strongly frequency dependent, and this dissipative process determines the width of the cyclotron resonance. The corresponding reactive effect determines the shift of the cyclotron resonance. It is shown that a correlation between line width maximum and zero frequency shift of the cyclotron mode exists, in agreement with experimental results. 相似文献
19.
Yu. A. Nefyodov A. A. Fortunatov A. V. Shchepetilnikov I. V. Kukushkin 《JETP Letters》2010,91(7):357-360
Electron spin resonance in a system of two-dimensional electrons with a high electron mobility has been investigated and the
position, width, intensity, and line shape of the resonance microwave absorption have been studied as functions of the filling
factor and temperature. It has been shown that the ESR linewidth in high-electron-mobility GaAs/AlGaAs quantum wells may reach
30 MHz, which corresponds to a spin relaxation time of the two-dimensional electrons of 10 ns. The experimental data on the
linewidth of the spin resonance at a filling factor of 1 are compared with the theoretical results for various spin relaxation
mechanisms. It has been shown that the dominant mechanism of spin relaxation at a filling factor of 1 and a temperature of
1.5–4 K is the mutual scattering of spin excitons. 相似文献
20.
Quantum cyclotron resonance of two-dimensional holes in strained germanium layers of the periodic heterostructure Ge-Ge1−x
Six has been observed and investigated for the first time. The results are compared with the data of electrophysical measurements
in strong magnetic fields. A clear dependence of the magnitude of the longitudinal effective mass of the holes on the absolute
magnitude of the elastic deformation of the germanium layers (splitting energy of the hole subbands) is observed.
Fiz. Tverd. Tela (St. Petersburg) 39, 2096–2100 (November 1997) 相似文献