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1.
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
2.
3.
A calculational scheme is presented to determine the density of states in the fluctuation tail for the disordered solid solution
ZnSe1−c
Tec at concentrations below the threshold for percolation over sublattice sites. Zero-phonon absorption and luminescence bands
in the region of the exciton ground state are found using an approach developed earlier. Phonon coupling is taken into account,
and vibronic absorption and luminescence bands are obtained. Experimental data are shown to be in a good agreement with the
calculations.
Fiz. Tverd. Tela (St. Petersburg) 40, 1420–1425 (August 1998) 相似文献
4.
A. A. Klochikhin 《Physics of the Solid State》1998,40(5):819-820
A unified method is developed for describing the steady-state luminescence of exciton fluctuation states for weak excitation
in different disordered systems. The phononless luminescence band is found to be formed by “radiative” states of the fluctuation
tail in the density of states, i.e., by states for which nonradiative states are either nonexistent or have a low probability.
The shape of the emission spectra calculated including the phonon interaction is in good agreement with experimental luminescence
spectra of α Si:H and of solid solutions of ZnSe(1−c)Tec and CdS(1−c)Sec.
Fiz. Tverd. Tela (St. Petersburg) 40, 890–891 (May 1998) 相似文献
5.
V. A. Moshnikov A. V. Moshnikov A. I. Rumyantseva S. A. Nemov R. V. Parfen’ev A. V. Chernyaev 《Physics of the Solid State》1999,41(4):550-555
A reliable technique of local chemical characterization of multicomponent semiconductor solid solutions has been developed,
and the possibility of its application to the SnTe-SnSe quaternary solid solutions doped with 16 at.% In verified. The behavior
of the electrical resistivity of samples of these solid solutions at low temperatures, 0.4–4.2 K, has been studied. The critical
temperature T
c and the second critical magnetic field H
c2 of the superconducting transition and their dependences on the solid-solution composition have been determined. The superconducting
transition at T
c≈2–3 K is due to hole filling of the In-impurity resonance states, and the observed variation of the superconducting transition
parameters with increasing Se content in the solid solution is related to the extrema in the valence band and the In band
of resonance states shifting with respect to one another.
Fiz. Tverd. Tela (St. Petersburg) 41, 612–617 (April 1999) 相似文献
6.
O. V. Ovchinnikov A. B. Evlev M. A. Efimova V. G. Klyuev A. N. Latyshev A. N. Utekhin A. M. Kholkina 《Journal of Applied Spectroscopy》2005,72(6):809-813
An anti-Stokes luminescence band with λmax = 515 nm of microcrystals of solid AgCl0.95I0.05 solutions excited by a radiation flux of density 1013–1015 quanta/cm2·sec in the range 600–800 nm at 77 K was detected. It is shown that the intensity of this luminescence and the frequency of
its excitation depend on the prior UV-irradiation of samples. Analysis of the stimulated-photoluminescence spectra and the
anti-Stokes luminescence excitation spectra of the indicated microcrystals has shown that to the centers of anti-Stokes luminescence
excitation correspond local levels in the forbidden band of the crystals. These states are apparently due to the atomic and
molecular disperse silver particles that can be inherent in character or formed as a result of a low-temperature photochemical
process.
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Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 72, No. 6, pp. 738–742, November–December, 2005. 相似文献
7.
The luminescence spectra are obtained in the visible region for the high-T
c superconductors La2CuO4, YBA2Cu3O7−δ
, Bi2Sr2CaCu2O8±δ
, and YBa2Cu3O8±δ
and for the secondary phases BaCuO2±γ and Y2Cu2O5. The presence of a luminescence band with energy E
lum∼2.4 eV in the spectra of all the investigated compounds is established. The nature of the observed luminescence bands is
discussed on the basis of a comparative analysis of the crystal structures and luminescence spectra and on the basis of notions
as to the presence of bands in the spectra accompanied by photoinduced diffusion of weakly bound oxygen and photoinduced charge
transfer in the CuO2 planes.
Fiz. Tverd. Tela (St. Petersburg) 39, 1739–1746 (October 1997) 相似文献
8.
Abstract Recombination luminescence emission spectra, TSL and trap spectra estimated by fractional glow technique (FGT), in nominally pure and Li-, Bi- and Ho-doped CdWO4, crystals are reported. According to the investigations by FGT heterovalent impurities Li, Bi and Ho causes localized electronic states which act as traps for charge carriers. It is shown that TSL results in emission of known blue-green luminescence band by emptying of the Li+-related traps in CdWO4-Li and yellow luminescence band by emptying of the Bi3+-related traps in CdWO4-Bi. It is proposed that blue-green and yellow luminescence occur by recombination correspondingly of free holes and free electrons at different intrinsic tungstate group related luminescence centers. 相似文献
9.
10.
A. N. Reznitskii A. V. Kornievskii A. A. Kiselev S. A. Permogorov L. N. Tenishev A. A. Klochikhin S. Yu. Verbin H. Gerlach M. Hetterich M. Grün C. Klingshirn 《Physics of the Solid State》1998,40(5):829-830
A theoretical and experimental study of the effect of a longitudinal magnetic field on optical orientation and magneto-circular
polarization of the luminescence of localized excitons in semiconducting solid solutions is reported. It is shown that recombination
takes place through two types of emitting states differing substantially in the degree of anisotropy, g factor, and spin relaxation time. Estimates are made of the g factors, anisotropic and exchange splittings, lifetime, and spin relaxation time of localized states in a CdS0.96Se0.04/GaAs solidsolution epitaxial layer.
Fiz. Tverd. Tela (St. Petersburg) 40, 900–902 (May 1998) 相似文献
11.
A theoretical interpretation is given of the fine structure in the total-current spectra obtained from the (0001) plane of
MoS2, ZrS2, and NbSe2 single crystals. The calculations took into account the energy dependences of band energy-level broadening and of the density
of unfilled electronic states which become occupied by electrons entering a solid. The dominant contribution of the bulk band
structure to the spectra is demonstrated.
Fiz. Tverd. Tela (St. Petersburg) 41, 1875–1878 (October 1999) 相似文献
12.
B. R. Namozov R. I. Zakharchenya M. P. Korobkov V. V. Mürk 《Physics of the Solid State》1998,40(4):599-600
Optical properties, including luminescence, of scandium-doped α-Al2O3 crystals have been studied in the VUV range. An absorption band associated with the scandium impurity was observed at the
fundamental-absorption edge of crystalline corundum. A strong luminescence band peaking at 5.6 eV, which is most effectively
excited within the 7.7–8.8-eV interval, was found. The kinetic and polarization characteristics of this luminescence were
studied within the temperature range 6–500 K. An excitation model of the impurity complex and the mechanism of its relaxation
are discussed.
Fiz. Tverd. Tela (St. Petersburg) 40, 653–654 (April 1998) 相似文献
13.
M. M. Chugunova I. A. Kamenskikh V. V. Mikhailin S. A. Usenko 《Optics and Spectroscopy》2010,109(6):887-892
We present the results of studying the luminescence properties of transparent ceramics Y3Al5O12:Yb obtained by the vacuum sintering and nanocrystalline technology. In the course of research, we measured the luminescence
and luminescence excitation spectra, as well as the temperature and kinetic behavior of luminescence. Our results are analyzed
in comparison with the characteristics of corresponding single crystals. We revealed that processes of generation and relaxation
of electronic excitations that occur in ceramics, in particular, in the charge transfer state, are similar to processes occurring
in crystals. The behavior of two charge-transfer luminescence bands at 340 and 490 nm is studied. In the range 300–600 nm,
we revealed a broad emission band of radiation of other type, which is also observed in spectra of undoped ceramics. This
broad band is attributed to F+ centers. Emission and excitation spectra of charge transfer luminescence at a maximum of the temperature dependence of 100
K are measured for the first time. We found that, upon excitation in the charge transfer band, luminescence in ceramics is
more intense than in single crystals with similar concentrations of Yb and has a higher quenching temperature. 相似文献
14.
Aleksandr Kalinko Alexey Kotlov Alexei Kuzmin Vladimir Pankratov Anatoli I. Popov Liana Shirmane 《Central European Journal of Physics》2011,9(2):432-437
The photoluminescence spectra and luminescence excitation spectra of pure microcrystalline and nano-sized ZnWO4 as well as the Zn
x
Ni1−x
WO4 solid solutions were studied using vacuum ultraviolet (VUV) synchrotron radiation. The samples were also characterized by
x-ray powder diffraction. We found that: (i) the shape of the photoluminescence band at 2.5 eV, being due to radiative electron
transitions within the [WO6]6− anions, becomes modulated by the optical absorption of Ni2+ ions in the Zn
x
Ni1−x
WO4 solid solutions; and (ii) no significant change in the excitation spectra of Zn0.9Ni0.1WO4 is observed compared to pure ZnWO4. At the same time, a shift of the excitonic bands to smaller energies and a set of peaks, attributed to the one-electron
transitions from the top of the valence band to quasi-localized states, were observed in the excitation spectrum of nano-sized
ZnWO4. 相似文献
15.
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
16.
The features of the intraband luminescence spectrum of wide-gap insulators (KI, KBr, CsCl, etc.) and semiconductors (GaP,
CdS, α-SiC, and ZnS) are studied in the temperature interval 80–760 K. The spectra of the intraband luminescence are compared with
the spectra of the pre-breakdown electroluminescence of GaP and α-SiC surface-barrier diode structures and of a ZnS thin-film electroluminescence indicator. In alkali halide crystals the
short-wavelength boundary hν
m of the intraband luminescence is less than the band gap E
g and is governed by complex excitonic processes. In semiconductors with indirect transitions hν
m>E
g. The differences in the spectra of the intraband luminescence and the intraband pre-breakdown electroluminescence can be
explained by differences in the distributions of the hot charge carriers over levels of the allowed bands and in the maximum
energies of the carriers involved in the formation of the spectra.
Fiz. Tverd. Tela (St. Petersburg) 39, 613–617 (April 1997) 相似文献
17.
G. O. Andrianov S. A. Nemov R. V. Parfen’ev D. V. Shamshur A. V. Chernyaev 《Physics of the Solid State》2010,52(9):1810-1814
This paper reports on a study of the low-temperature conductivity and parameters of the superconducting state, namely, the
critical temperature T
c
and the second critical magnetic field Hc2, in the (Pb0.3Sn0.7)0.95In0.05Te solid solution under hydrostatic pressure P ≤ 9 kbar at T = 4.2 K. The choice of this material has been motivated by the fact that, according to earlier observations, it undergoes
a superconducting transition at T
c
∼ 2.3 K, i.e., close to the maximum value T
c
∼ 2.9 K found for the (Pb
z
Sn1 − z
)0.95In0.05Te solid solutions with a lead content z ∼ 0.15–0.25. It has been demonstrated that an increase in the pressure to P ≤ 9 kbar leads to a bell-shaped dependence T
c
(P). The observed dependences are assigned to the effect of hydrostatic compression on the band structure of the solid solution
and indicate a shift in the position of the Fermi level E
F with increasing pressure within the impurity band of the In quasi-local states. In this case, E
F passes through a maximum in the density of impurity states at P = 3–5 kbar. 相似文献
18.
The deviation from the Nordheim-Kurnakov rule and the anomalous behavior of spin-disordered electrical resistivity in quasi-binary
GdZn (T
C
=268 K)-GdCu (T
N
=142 K) solid solutions is explained in effective medium approximation within percolation theory for the case of three phases,
viz., ferro-, antiferro-, and paramagnetic. The strong increase of ρ at zinc concentrations x∼0.45 is attributed to the closeness of the system to the percolation threshold. The phase volumes calculated for the random-distribution
case fit well to the concentration dependence of magnetic susceptibility.
Fiz. Tverd. Tela (St. Petersburg) 40, 974–979 (June 1998) 相似文献
19.
A. V. Akimov E. S. Moskalenko A. L. Zhmodikov D. A. Mazurenko A. A. Kaplyanskii L. J. Challis T. S. Cheng C. T. Foxon 《Physics of the Solid State》1997,39(4):649-653
We report the first studies of exciton luminescence spectra from asymmetric double quantum wells (DQWs) of very similar width.
The DQWs were of GaAs/AlGaAs and the differences in widths of the coupled wells were one or two monolayers. The coupled direct
and indirect exciton states anticross with a resonance splitting of 1.33 meV. An additional luminescence line appearing at
low temperatures is identified as a localized indirect exciton.
Fiz. Tverd. Tela (St. Petersburg) 39, 735–739 (April 1997) 相似文献
20.
The electrical properties of (Co45Fe45Zr10)x(Al2O3)1−x
granular nanocomposites have been studied. The concentration dependences of electrical resistivity are S-shaped (in accordance with the percolation theory of conduction) with a threshold at a metallic component concentration of
∼41 at. %. An analysis of the temperature behavior carried out in the range 300–973 K revealed that structural relaxation
and crystallization of the amorphous phase are accompanied by a decrease in the electrical resistivity of the composites above
the percolation threshold and by its increase below the percolation threshold. For metallic phase concentrations x<41 at. %, variable range hopping conduction over localized states near the Fermi level was found to be dominant at low temperatures
(77–180 K). A further increase in temperature brings about a crossover of the conduction mechanism from Mott’s law ln(σ) ∝
(1/T)1/4 to ln(σ) ∝ (1/T)1/2. A model of inelastic resonance tunneling over a chain of localized states of the dielectric matrix was used to find the
average number of localized states involved in the charge transport between metallic grains.
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Translated from Fizika Tverdogo Tela, Vol. 46, No. 11, 2004, pp. 2076–2082.
Original Russian Text Copyright ? 2004 by Kalinin, Remizov, Sitnikov. 相似文献