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1.
R. I. Dzhioev B. P. Zakharchenya E. L. Ivchenko V. L. Korenev Yu. G. Kusraev N. N. Ledentsov V. M. Ustinov A. E. Zhukov A. F. Tsatsul’nikov 《JETP Letters》1997,65(10):804-809
The experimental results of a study of the fine structure of the levels of excitons localized in InAlAs quantum dots in an
AlGaAs matrix are reported. Transformations from optical orientation to alignment and from alignment to orientation, which
occur due to the exchange splitting of a dipole-active excitonic doublet and are allowed by the low symmetry of a quantum
dot, are observed in a longitudinal magnetic field (Faraday geometry). A comparison of theory with experiment for a self-organized
ensemble of quantum dots enables a determination of the character of the distribution over the dipole orientations for resonance
optical transitions.
Pis’ma Zh. éksp. Teor. Fiz. 65, No. 10, 766–771 (25 May 1997) 相似文献
2.
R. I. Dzhioev B. P. Zakharchenya E. L. Ivchenko V. L. Korenev Yu. G. Kusraev N. N. Ledentsov V. M. Ustinov A. E. Zhukov A. F. Tsatsul’nikov 《Physics of the Solid State》1998,40(5):790-793
Optical orientation and alignment of excitons in InAlAs quantum dots in the AlGaAs matrix have been studied both theoretically
and experimentally. Experiments performed in a longitudinal magnetic field (Faraday geometry) reveal transformation of optical
orientation to alignment and alignment to orientation, which is caused by exchange splitting of the dipole-active exciton
doublet and allowed by the quantum-dot low symmetry. A comparison of theory with experiment made with inclusion of the anisotropy
of exciton generation and recombination along the
and [110] axes permits one to determine the character of dipole distribution in direction for resonant optical transitions
in the self-organized quantum-dot ensemble studied.
Fiz. Tverd. Tela (St. Petersburg) 40, 858–861 (May 1998) 相似文献
3.
The evolution of indirect exciton luminescence in AlAs/GaAs coupled quantum wells after excitation by pulsed laser radiation
has been studied in strong magnetic fields (B⩽12 T) at low temperatures (T⩾1.3 K), both in the normal regime and under conditions of anomalously fast exciton transport, which is an indication of the
onset of exciton superfluidity. The energy relaxation rate of indirect excitons measured in the range of relaxation times
between several and several hundreds of nanoseconds is found to be controlled by the properties of the exciton transport,
specifically, this parameter increases with the coefficient of excitonic diffusion. This behavior is qualitatively explained
in terms of migration of excitons between local minima of the random potential in the plane of the quantum well.
Zh. éksp. Teor. Fiz. 114, 1115–1120 (September 1998) 相似文献
4.
V. B. Timofeev A. I. Tartakovskii A. I. Filin D. Birkedal J. Hvam 《Physics of the Solid State》1998,40(5):767-769
Luminescence and luminescence excitation spectra are used to study the energy spectrum and binding energies of direct and
spatially indirect excitons in GaAs/AlGaAs superlattices having different electron and hole miniband widths in high magnetic
fields perpendicular to the heterolayers. The ground state of the indirect excitons formed by electrons and holes which are
spatially distributed among neighboring quantum wells is found to lie between the ground 1s state of the direct excitons and the threshold of the continuum of dissociated exciton states in the minibands. The indirect
excitons have a substantial oscillator strength when the binding energy of the exciton exceeds the scale of the width of the
resulting miniband. It is shown that a high magnetic field shifts a system of symmetrically bound quantum wells toward weaker
bonding. At high exciton concentrations, spatially indirect excitons are converted into direct excitons through exciton-exciton
collisions.
Fiz. Tverd. Tela (St. Petersburg) 40, 833–836 (May 1998) 相似文献
5.
V. A. Kosobukin 《Physics of the Solid State》1998,40(5):758-760
A theory of light absorption by excitons in periodic structures with an arbitrary number of quantum wells is constructed.
It is shown that the temperature dependence of the frequency-integrated absorption characteristics is due to a competition
between the processes of dissipative decay of quasi-two-dimensional excitons and the light-exciton interaction.
Fiz. Tverd. Tela (St. Petersburg) 40, 824–826 (May 1998) 相似文献
6.
Kh. Moumanis R. P. Seisyan M. É. Sasin A. V. Kavokin S. I. Kokhanovskii H. M. Gibbs G. Khitrova 《Physics of the Solid State》1998,40(5):731-733
Additional localization of holes due to Coulomb attraction to the electron located in a quantum well is important for light-hole
excitons in the heterostructure (In, Ga)As/GaAs. The fine structure of the optical and magneto-optical spectra of these quantum
wells is examined in detail with the formation of a “Coulomb well” and deformations taken into account.
Fiz. Tverd. Tela (St. Petersburg) 40, 797–799 (May 1998) 相似文献
7.
The ratio of the densities of intra-and interwell excitons in a symmetric system of coupled quantum wells — a superlattice
based on a GaAs/AlGaAs heterostructure — is investigated over a wide range of optical excitation power densities. Conversion
of interwell excitons into intrawell excitons as a result of exciton-exciton collisions is observed at high exciton densities.
Direct evidence for such a conversion mechanism is the square-root dependence of the interwell exciton density on the optical
excitation level. The decrease in the lifetime of interwell excitons with increasing excitation density, as measured directly
by time-resolved spectroscopy methods, confirms the explanation proposed for the effect.
Pis’ma Zh. éksp. Teor. Fiz. 65, No. 8, 623–628 (25 April 1997) 相似文献
8.
V. D. Kulakovskii L. V. Kulik A. L. Yablonskii A. B. Dzyubenko N. A. Gippius S. G. Tikhodeev A. Forchel 《Physics of the Solid State》1998,40(5):740-742
We have measured the photoluminescence spectra and photoluminescence excitation spectra of magnetic excitons in InGaAs/GaAs
near-surface quantum wells in a magnetic field. We have quantitatively investigated the effect of dielectric enhancement of
excitons in quantum wells brought about by decreasing the thickness of the barrier layer, both in a magnetic field and without.
Fiz. Tverd. Tela (St. Petersburg) 40, 806–808 (May 1998) 相似文献
9.
L. V. Butov A. V. Mintsev A. I. Filin K. Eberl 《Journal of Experimental and Theoretical Physics》1999,88(5):1036-1044
The kinetics of indirect photoluminescence of GaAs/AlxGa1−x
As double quantum wells, characterized by a random potential with a large amplitude (the linewidth of the indirect photoluminescence
is comparable to the binding energy of an indirect exciton) in magnetic fields B≤12 T at low temperatures T≥1.3 K is investigated. It is found that the indirect-recombination time increases with the magnetic field and decreases with
increasing temperature. It is shown that the kinetics of indirect photoluminescence corresponds to single-exciton recombination
in the presence of a random potential in the plane of the double quantum wells. The variation of the nonradiative recombination
time is discussed in terms of the variation of the transport of indirect excitons to nonradiative recombination centers, and
the variation of the radiative recombination time is discussed in terms of the variation of the population of optically active
excitonic states and the localization radius of indirect excitons. The photoluminescence kinetics of indirect excitons, which
is observed in the studied GaAs/AlxGa1−x
As double quantum wells for which the random potential has a large amplitude, is qualitatively different from the photoluminescence
kinetics of indirect excitons in AlAs/GaAs wells and GaAs/AlxGa1−x
As double quantum wells with a random potential having a small amplitude. The temporal evolution of the photoluminescence
spectra in the direct and indirect regimes is studied. It is shown that the evolution of the photoluminescence spectra corresponds
to excitonic recombination in a random potential.
Zh. éksp. Teor. Fiz. 115, 1890–1905 (May 1999) 相似文献
10.
A. I. Tartakovskii V. B. Timofeev V. G. Lysenko D. Birkedal J. Hvam 《Journal of Experimental and Theoretical Physics》1997,85(3):601-608
Luminescence and luminescence excitation spectra are used to study the energy spectrum and binding energies of direct and
spatially indirect excitons in GaAs/AlaAs superlattices, with different widths of the electron and hole minibands, located
in a high magnetic field perpendicular to the heterolayers. It is found that the ground state of the indirect excitons formed
by electrons and holes and spatially separated between neighboring quantum wells lies between the ls ground state of the direct excitons and the continuum threshold for dissociated exciton states in the minibands. Indirect
excitons in superlattices have a significant oscillator strength when the binding energy of the exciton exceeds the order
of the width of the resulting miniband. The behavior of the binding energy of direct and indirect heavy hole excitons during
changes in the tunneling coupling between the quantum wells is established. It is shown that a strong magnetic field, which
intensifies the Coulomb interaction between the electron and hole in an exciton, weakens the bond in a system of symmetrically
bound quantum wells. The spatially indirect excitons studied here are analogous to first order Wannier-Stark localized excitons
in superlattices with inclined bands (when an electrical bias is applied), but in the present case the localization is of
purely Coulomb origin.
Zh. éksp. Teor. Fiz. 112, 1106–1118 (September 1997) 相似文献
11.
Time-resolved pulsed spectroscopy was used to measure the luminescence spectra of calcium fluoride. Characteristic features
of the luminescence of self-trapped excitons are discussed. It is shown that various configurations of self-trapped excitons
incorporating hole nuclei of a more complex structure, may be formed in CaF2 crystals.
Fiz. Tverd. Tela (St. Petersburg) 40, 1226–1227 (July 1998) 相似文献
12.
The change in the properties of excitonic states near anticrossing is investigated experimentally. It is shown that the phase
relaxation time of light excitons in a GaAs/AlGaAs symmetric double quantum well increases by a factor of five as a result
of mixing of the energy states of light and heavy excitons.
Pis’ma Zh. éksp. Teor. Fiz. 69, No. 6, 426–430 (25 March 1999) 相似文献
13.
V. A. Kosobukin 《Physics of the Solid State》1998,40(2):332-335
The propagation of exciton polaritons in an optical waveguide with a quantum well is studied. Spatial dispersion of the excitons
causes the wave vector of the exciton polaritons to split between waveguide and exciton modes at resonance. The magnitude
of this splitting is determined by the radiative decay parameter of excitons with corresponding polarization in the quantum
well. The group velocity of the waveguide exciton polaritons in the resonance region can be three or four orders of magnitude
lower than the speed of light in vacuum.
Fiz. Tverd. Tela (St. Petersburg) 40, 362–365 (February 1998) 相似文献
14.
R. I. Dzhioev B. P. Zakharchenya V. L. Korenev M. V. Lazarev 《Physics of the Solid State》1999,41(12):2014-2019
Magnetic interaction between spin-polarized nuclei and optically oriented excitons in a self-organized ensemble of size-quantized
InP islands in an InGaP matrix has been studied in a magnetic field in Faraday geometry. The effective magnetic fields generated
by polarized nuclei at excitons have been measured. The strengths of these fields were found to be different for active and
inactive excitons because of the difference between the excitonic g factors. The heavy-hole g factor has been determined. The active and inactive excitonic states were found to be coupled through cross-relaxation.
Fiz. Tverd. Tela (St. Petersburg) 41, 2193–2199 (December 1999) 相似文献
15.
The observation of optical orientation of excitons and the Hanle effect in an asymmetric CdTe/CdMnTe double quantum well is
reported. The characteristics of the magnetic depolarization of radiation from CdTe/CdMnTe quantum wells are discussed.
Pis’ma Zh. éksp. Teor. Fiz. 63, No. 4, 241–245 (25 February 1996) 相似文献
16.
A. A. Rogachev 《Physics of the Solid State》1998,40(5):855-857
Excitons in many-valley semiconductors form molecules consisting of four and more excitons. The degeneracy factor g of the conduction band in germanium is 8, and in silicon g=12. As in acceptors, the hole ground state in excitons is fourfold degenerate. The same is valid for exciton molecules, because
they are quantum objects with spherical symmetry. The exciton binding energy in molecules is close to that in exciton-liquid
droplets. Experimental evidence is considered for the existence, besides biexcitons, of stable exciton molecules consisting
of three and four, and, possibly, 11 and 12 excitons. Molecules containing from five to ten excitons are apparently unstable.
Fiz. Tverd. Tela (St. Petersburg) 40, 929–931 (May 1998) 相似文献
17.
Yasuo Oka 《Physics of the Solid State》1998,40(5):778-780
Excitonic properties and the dynamics are reported in quantum dots (QDs) and quantum wells (QW) of diluted magnetic semiconductors.
Transient spectroscopies of photoluminescence and nonlinear-optical absorption and emission have been made on these quantum
nanostructures. The Cd1−x
MnxSe QDs show the excitonic magnetic polaron effect with an increased binding energy. The quantum wells of the Cd1−x
MnxTe/ZnTe system display fast energy and dephasing relaxations of the free and localized excitons as well as the tunneling process
of carriers and excitons in the QWs depending on the barrier widths. The observed dynamics and the enhanced excitonic effects
are the inherent properties of the diluted magnetic nanostructures.
Fiz. Tverd. Tela (St. Petersburg) 40, 846–848 (May 1998)
Published in English in the original Russian journal. Reproduced here with stylistic changes by the Translation Editor. 相似文献
18.
Yu. A. Gol’dberg O. V. Konstantinov O. I. Obolenskii E. A. Posse 《Physics of the Solid State》1998,40(5):870-871
A new excitonic mechanism for decreasing the quantum efficiency of the photoelectric conversion process in surface-barrier
structures is considered. This mechanism involves the formation of hot excitons which have a large ionization energy and are
not subject to the influence of the barrier electric field. The spectral dependence of the hot photocarrier losses is derived
in an explicit form from experimental data on the basis of a previously proposed model and is analyzed. This dependence has
two segments with abrupt increases, which are caused by the formation of excitons in the L and X valleys of the semiconductor.
Fiz. Tverd. Tela (St. Petersburg) 40, 944–945 (May 1998) 相似文献
19.
A. N. Izotov V. V. Kveder Yu. A. Osip’yan É. A. Steinman R. K. Nikolaev N. S. Sidorov 《Journal of Experimental and Theoretical Physics》1998,87(6):1205-1213
The absorption coefficient of perfect single crystals of the fullerene C60 is measured in the energy range 1.6–2.1 eV at temperatures from 4.2 to 300 K. An absorption fine structure is discovered
in the and is assigned to electronic and vibronic transitions with the production of free excitons and excitons localized
on structural defects. It is shown that in the region of the structural phase transition from a face-centered cubic structure
to a simple cubic structure the absorption coefficient undergoes a jump, which is associated with an energy shift of the free
exciton line toward lower energies. It is discovered that spatial inhomogeneity, which is associated with the growth of the
new phase from a finite number of nuclei, appears in the crystal at the time of this transition.
Zh. éksp. Teor. Fiz. 114, 2211–2224 (December 1998) 相似文献
20.
Korenev VL 《Physical review letters》2007,99(25):256405
Linearly polarized light tuned slightly below the optical transition of the negatively charged exciton (trion) in a single quantum dot causes the spontaneous nuclear spin polarization (self-polarization) at a level close to 100%. The effective magnetic field of spin-polarized nuclei shifts the optical transition energy close to resonance with photon energy. The resonantly enhanced Overhauser effect sustains the stability of the nuclear self-polarization even in the absence of spin polarization of the quantum dot electron. As a result the optically selected single quantum dot represents a tiny magnet with the ferromagnetic ordering of nuclear spins-the nuclear spin nanomagnet. 相似文献