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1.
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
2.
N. N. Ledentsov R. Nötzel P. S. Kop'ev K. Ploog 《Applied Physics A: Materials Science & Processing》1992,55(6):533-536
Hot exciton relaxation is observed in GaAs/Al
x
Ga1–x
As multiple quantum wells. The photolumnescence excitation spectra of the localized exciton emission at low temperatures and excitation densities are composed of narrow equidistant peaks exactly separated by the GaAs LO-phonon energy (36 meV). The relaxation mechanism via LO-phonons is found to be important for localized excitons in multiple quantum wells with GaAs layer thicknesses of about 50 Å, where pronounced alloy fluctuations in the barriers provide a strong additional lateral potential which suppresses the dissociation of hot excitons. 相似文献
3.
A. V. Chernenko N. G. Kalugin O. A. Kusnetsov 《Journal of Experimental and Theoretical Physics》1998,87(2):337-341
This paper reports on the first investigation made of luminescence of Ge/Ge1−x
Six heterostructures at liquid-helium temperatures in a magnetic field of up to 14 T. The luminescence lines observed in the
spectra are due to both free and impurity bound excitons in Ge layers. The diamagnetic shift of the quasi-two-dimensional
exciton has been measured. From the experimental data the size of the exciton has been estimated to be 75–90 Å.
Zh. éksp. Teor. Fiz. 114, 619–627 (August 1998) 相似文献
4.
The Zeeman splitting of the ground states 1s(hh) and 1s(lh) of excitons with heavy and light holes, respectively, in a 15-nm isolated Al0.3Ga0.7As/GaAs quantum well in magnetic fields of up to 20 T is investigated according to the photoluminescence excitation spectra
in the Faraday geometry (σ+− σ− components). The observed anomalous pattern of nonlinear Zeeman splitting and the nonmonotonic behavior of the effective
hole g factor are interpreted in terms of the strong mixing of the magnetoexcitonic states containing light and heavy holes.
Pis'ma Zh. éksp. Teor. Fiz. 64, No. 1, 52–56 (10 July 1996) 相似文献
5.
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
6.
Yu. P. Gnatenko O. A. Shigil’chev E. Rutkovskii G. Contreras-Puente M. Cardenas-Garcia 《Physics of the Solid State》1998,40(4):564-568
Low-temperature photoluminescence, exciton reflection, and multiphonon resonant Raman scattering spectra of Ni-and Co-doped
Zn1−x
MnxTe crystals were investigated. Intense emission occurs in a broad spectral region (1100–17 000 cm−1) in the crystals containing Ni atoms. It is caused by intracenter transitions involving Mn2+ ions and transitions between the conduction band and a level of the doubly charged acceptor. The features of the exciton
photoluminescence and multiphonon resonant Raman scattering involving longitudinal-optical (LO) phonons at various temperatures
are investigated. The insignificant efficiency of the localization of excitons on potential fluctuations in the Zn1−x
MnxTe:Co crystals is established. A temperature-induced increase in the intensity of the 5LO multiphonon resonant Raman scattering
line due to the approach of the conditions for resonance between this line and the ground exciton state is observed in these
crystals.
Fiz. Tverd. Tela (St. Petersburg) 40, 616–621 (April 1998) 相似文献
7.
The form of the stationary luminescence spectra of excitons, localized by composition fluctuations, in disordered solid solutions
under weak excitation is calculated. The tail states for which there are no nonradiative transition channels are distinguished
by means of continuum percolation theory. Such states are responsible for the “zero-phonon” luminescence band. The shape of
the short-wavelength luminescence band edge is determined mainly by the number of isolated localizing clusters and their smallest
complexes, which decreases rapidly near the mobility threshold. The real luminescence spectrum is due to the simultaneous
emission of phonons. The phonon emission determines the form of the long-wavelength wing of the emission band. The computed
shape of the emission spectrum is compared with the experimental luminescence spectra of the solid solution CdS(1−c)Sec.
Pis’ma Zh. éksp. Teor. Fiz. 65, No. 3, 274–279 (10 February 1997) 相似文献
8.
9.
The exciton absorption spectra of thin films of (Cs1 − x
Rb
x
)2CdI4 solid solutions have been investigated and the refractive index n(λ) in their transparency window in the concentration range of 0 ≤ x ≤ 1 has been measured. The exciton-band parameters and optical permittivity ɛ∞(x) have been found to linearly depend on the concentration. It is established that excitons are incorporated into the CdI2 sublattice of the solid solutions and belong to intermediate-coupling ones. The characteristics of excitons in ferroelastics
are compared with the corresponding parameters for CdI2, RbI, and CsI, which are used as components to synthesize ternary compounds. 相似文献
10.
An analysis is made of the exciton angular-momentum alignment along a fluctuation in local magnetization, which is the first
stage in evolution of the localized-exciton spin state in a semimagnetic semiconductor. It is shown that spin relaxation of
localized excitons subjected to resonant optical excitation is accompanied by their relaxation in energy. When excited by
polarized light, this process gives rise to an anisotropic angular-momentum distribution in the spectrum of final exciton
states and, hence, to polarization of the secondary luminescence. Luminescence spectra of a cubic crystal are calculated,
and the possibility of their experimental observation discussed.
Fiz. Tverd. Tela (St. Petersburg) 40, 2156–2160 (December 1998) 相似文献
11.
V. R. Galakhov M. Neumann D. G. Kellerman 《Applied Physics A: Materials Science & Processing》2009,94(3):497-500
X-ray absorption, resonant X-ray emission, and X-ray photoelectron spectroscopical methods have been applied for the study
of the electronic structure of defective lithium cobaltites Li
x
CoO2 (0.6≤x≤1.0). Resonant O K
α X-ray emission spectra of LiCoO2 showed localized excitonic states due to a dd transition between occupied and unoccupied Co 3d states. On the base of measurements of Co 3s X-ray photoelectron, Co 2p, and O 1s X-ray absorption spectra, it was established that in defective cobaltites the electronic holes are localized mainly in O
2p states. An evidence of phase separation in Li
x
CoO2 has been found. It was shown that the semiconductor-to-metal transition in Li
x
CoO2 (x<0.76) at about 160 K is not accompanied by changes in the Co 3d electronic configuration which remains 3d
6. 相似文献
12.
Low temperature emission spectra of localized excitons in CdS1?xSex solid solutions under the monochromatic excitation with tunable laser have been studied. It has been found that the luminescence of localized excitons has a high degree of linear polarization with respect to the polarization direction of exciting light. This polarization reflects the “hidden” anisotropy of macroscopically isotropic localized exciton system and strongly depends on the frequency of exciting light. Study of this dependence has permitted for the first time a determination of position of the “mobility edge” for exciton migration in disordered semiconductor solid solution. 相似文献
13.
A. B. Dzyubenko 《Journal of Experimental and Theoretical Physics》1998,86(4):790-797
A theory of far-infrared (FIR) magneto-optical intraband s→p
± transitions of direct and indirect excitons in semiconductor coupled double quantum wells has been developed. The case of
symmetric strained InxGa1−x
As/GaAs quantum wells with nondegenerate valence band in the regime of both narrow and wide barriers has been analyzed. The
energies and dipole matrix elements of transitions between the ground s and excited p
± states in a quantizing magnetic field B>2 T and electric field ℰ perpendicular to the quantum well plane have been studied. The regimes of direct (in a weak electric
field) and indirect (in a strong electric field) transitions, and the transition between the direct and indirect regimes,
have been investigated.
Zh. éksp. Teor. Fiz. 113, 1446–1459 (April 1998) 相似文献
14.
E. A. Mulyarov N. N. Sibel’din M. L. Skorikov V. A. Tsvetkov B. Etienne 《JETP Letters》1999,70(9):621-627
Lines corresponding to localized excitonic states formed from “above-barrier” electron and/or hole states (specifically, excitation
lines of excitons formed by an electron localized in a QW and a free heavy hole) have been observed in the photoluminescence
excitation spectra of GaAs/Al0.05Ga0.95As structures with quantum wells (QWs), each containing one single-particle size-quantization level for charge carriers of
each type. A computational method is proposed that permits finding the binding energy and wave functions of excitons in QWs
taking the Coulomb potential into account self-consistently. The computed values of the excitonic transition energies agree
quite well with the experimental results.
Pis’ma Zh. éksp. Teor. Fiz. 70, No. 9, 613–619 (10 November 1999) 相似文献
15.
V. S. Bagaev V. S. Krivobok V. P. Martovitsky A. V. Novikov 《Journal of Experimental and Theoretical Physics》2009,109(6):997-1010
The germanium distribution in Si(001)/Si1 − x
Ge
x
layers as a function of the layer thickness at a low dopant concentration (x < 6%) has been investigated using high-resolution X-ray diffractometry and low-temperature photoluminescence. It has been
shown that the germanium concentration increases with increasing thickness of the SiGe layer with the formation of lateral
inhomogeneities at the boundary between this layer and a silicon cap layer for a layer thickness of 30 nm or more. These inhomogeneities
have an oriented character and give rise to anisotropic diffuse scattering for the system of (113) and (224) asymmetric reflections
from SiGe. The luminescence of these films at low temperatures and low excitation densities is an emission of localized and
delocalized excitons, which is characteristic of systems with disorder. The revealed nonuniform germanium distribution in
the lateral direction is associated with the accumulation of germanium in the near-surface SiGe layer and with the partial
relaxation of elastic strains due to the development of surface roughness and the preferred incorporation of germanium atoms
into one side of the surface ripples. 相似文献
16.
The pump-probe experimental method is used to investigate the effect of photoexcited carriers on the dynamics of the exciton
absorption spectra of GaAs / AlxGa1–x
As-multilayer quantum wells. Use of the method of moment analysis for processing the results makes it possible to identify
the simultaneous contribution of changes in oscillator strength and width of the exciton lines in the saturation of exciton
absorption. It was found that the oscillator strength recovers its initial value in the course of the first 100–130 ps, whereas
broadening and energy-shift of the exciton lines is observed for 700–800 ps. These are the first experimental measurements
of the excitation densities at which the oscillator strength of the excitonic state saturates when the latter is perturbed
only by free-electron-hole pairs, and when it is perturbed only by other excitons.
Fiz. Tverd. Tela (St. Petersburg) 40, 1130–1133 (June 1998) 相似文献
17.
I. Kh. Akopyan B. V. Bondarenko O. N. Volkova B. V. Novikov T. A. Pavlova 《Physics of the Solid State》1997,39(1):58-63
Low-temperature (4.2–130 K) photoluminescence spectra of HgI2 crystals have been measured in the 540–700 nm region. An analysis of the characteristics (intensity vs temperature and excitation
power relations, afterglow times, excitation spectra) of the 560, 620, and 635 nm emission bands suggests the following assignments:
the 560 nm band is due to radiative annihilation of excitons bound to mercury vacancies, and the “red” emission originates
from recombination of free (620 nm) and donor-localized (635 nm) electrons with a hole-filled acceptor level. The energies
of the corresponding donor and acceptor levels have been estimated. New emission bands at 540, 545, and 575 nm have been discovered,
and their origin discussed.
Fiz. Tverd. Tela (St. Petersburg) 39, 67–73 (January 1997) 相似文献
18.
The influence of photoexcited carriers on the dynamics of the absorption spectra of GaAs/AlxGa1−2x
As multilayer quantum wells is investigated experimentally. It is found that at quasiparticle densities all the way up to
1011 cm−2 the saturation of the excitonic absorption is due to both a decrease of oscillator strength and broadening of the excitonic
lines. It is shown that in the case of femtosecond resonance laser exci-tation the decrease of oscillator strength is due
to free electron-hole pairs, while the broadening and energy shift of the excitonic lines are due to the exciton-exciton interaction.
The lifetimes of free electron-hole pairs and excitons (≈65 ps and ≈410 ps, respectively) are determined from the exponential
decrease of the change in the oscillator strength and in the width and energy position of the excitonic lines.
Pis’ma Zh. éksp. Teor. Fiz. 66, No. 3, 139–144 (10 August 1997) 相似文献
19.
The short-range order in amorphous SiO
x
(0 ≤ x ≤ 2) films has been studied by high-resolution X-ray photoelectron spectroscopy. Both the random bonding and random mixture
models do not describe experimental photoelectron spectra of SiO
x
(x ≤ 2). An intermediate model of the SiO
x
structure has been proposed. The measured photoelectron spectra of the SiO
x
(x ≤ 2) valence band indicate the presence of the silicon phase and silicon oxide. 相似文献
20.
O. A. Usov K. Yu. Pogrebitskii B. T. Melekh Yu. N. Yur’ev Se Ahn Song 《Physics of the Solid State》1999,41(5):811-813
The fine structure in the titanium x-ray K-edge absorption has been measured in Ti1−x
NbxO2 mixed dioxides (x=0–0.1) with rutile structure in a laboratory-type spectrometer by total electron quantum-yield measurement. The position
of the XANES lines is shown to be in good agreement with classical x-ray absorption spectra obtained in transmission. The
structure and main features of the XANES spectra, including the effects of impurities and manyelectron excitations, are discussed.
It is suggested that the intensity of the B peak characteristic of the titanium K edge depends on the Nb concentration and correlates with the charge state of titanium ions.
Fiz. Tverd. Tela (St. Petersburg) 41, 894–896 (May 1999) 相似文献