共查询到20条相似文献,搜索用时 15 毫秒
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《Superlattices and Microstructures》1993,13(3):315
The absorption coefficient spectrum of undoped, disordered InGaAs/GaAs single quantum wells is calculated within the parabolic band approximation in this compressively strained structure. Results are presented for light propagating normal to and along the plane of the quantum well, taking into consideration the 1S-like exciton and all bound states, including the 2D enhancement Sommerfeld factor. The results presented here show that the exciton peaks in TE polarization remain constant with disordering and exhibit a larger wavelength shift than in TM polarization. The absorption edge in disordered InGaAs/GaAs, which is a function of the strain and interdiffusion, can be tailored to the desired wavelength around 1.0 μm. These results can be of interest in the design of photonic devices on a single substrate. 相似文献
3.
M.S. Brodin I.V. Blonskii B.M. Nitsovich A.S. Krochuk A.V. Franiv 《Solid State Communications》1982,44(2):181-185
Anomalies in the temperature dependence of the integral characteristics of exciton light absorption in layer crystals are found. To explain these, the mechanisms of exciton excitation energy relaxation are first proposed which take into account the specific features of a dissipative subsystem in layer crystals, the occurrence of bending waves in the spectrum of acoustic phonons and of low-energy optic phonons. 相似文献
4.
It is shown that, because the shape of the exciton absorption curve in crystalline TlGaS2 is described by the Fano antiresonance profile, the experimentally observed exciton peak corresponds to a modified state which is the result of the configuration interaction of a discrete state (exciton) with the quasi-continuum of conduction-band states. The oscillator strength for the transition to the discrete (“pure”) exciton state is calculated as F 0=1.22×10?2. The exciton transition selection rules are calculated for two assumed symmetry groups, D 2h and D 4h . An analysis of the selection rules for the dipole-allowed exciton transition permits one to conclude that the symmetry group for the TlGaS2 crystal is D 2h . 相似文献
5.
We analyze the exciton states in a quantum wire under intense laser radiation. Electrons and holes are confined by the parabolic potential of the quantum wire. An exactly solvable model is introduced for calculating the exciton binding energy, replacing the actual Coulomb interaction between the electron and the hole by a projective operator. 相似文献
6.
《Journal of Physics and Chemistry of Solids》1986,47(9):895-898
Electrical conduction at 77 K in CdxHg1−xTe, with the composition x ⩽ 0.2, is by electrons in the conduction band, by holes in the valence band and by holes in the impurity band. In samples with zero energy gap, x < 0.14, electrical conduction by holes in the valence band is comparable to electrical conduction by holes in the impurity band. In the open energy gap CdHgTe, electrical conduction by holes in the valence band is negligible in comparison to electrical conduction by holes in the impurity band. In CdHgTe samples, electrical conduction in the impurity band is described by the “Fermi Glass” model. 相似文献
7.
S. V. Budakovskii V. V. Gruzinskii S. V. Davydov É. É. Kolesnik 《Journal of Applied Spectroscopy》1991,54(1):60-64
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 54, No. 1, pp. 79–83, January, 1991. 相似文献
8.
U. Rössler 《Solid State Communications》1984,49(10):943-947
The dispersion of the conduction band in GaAs is calculated using k·p models which in different ways take into account the coupling to the p-bonding and p-antibonding states. Nonparabolicity, warping and spin-splitting are accurately described up to energies about 50 meV above the conduction band minimum by the 8×8 Kane model. For higher energies a 14×14 matrix is required. 相似文献
9.
Ellchi Hanamura 《Optical and Quantum Electronics》1989,21(6):441-450
Excitons are shown to enhance third-order optical susceptibilityx
(3) and shorten its response timeT
1 in suitable low-dimensional crystals; for example, a system of semiconductor microcrystallites and a natural and artificial quantum-well system. Some experimental evidence of enhancedx
(3) and shortenedT
1 is also introduced. 相似文献
10.
Burch KS Shrekenhamer DB Singley EJ Stephens J Sheu BL Kawakami RK Schiffer P Samarth N Awschalom DD Basov DN 《Physical review letters》2006,97(8):087208
The band structure of a prototypical dilute magnetic semiconductor (DMS), Ga1-xMnxAs, is studied across the phase diagram via infrared and optical spectroscopy. We prove that the Fermi energy (EF) resides in a Mn-induced impurity band (IB). Specifically the changes in the frequency dependent optical conductivity [sigma1(omega)] with carrier density are only consistent with EF lying in an IB. Furthermore, the large effective mass (m*) of the carriers inferred from our analysis of sigma1(omega) supports this conclusion. Our findings demonstrate that the metal to insulator transition in this DMS is qualitatively different from other III-V semiconductors doped with nonmagnetic impurities. We also provide insights into the anomalous transport properties of Ga1-xMnxAs. 相似文献
11.
An exciton in a spherical quantum dot is studied analytically within the effective mass approximation. A parabolic confinement under an electric field is considered. The linear and nonlinear optical absorption coefficients are calculated within the density matrix formalism. No assumptions are made about the strength of the confinement. It is shown how the competing mechanisms of the Coulomb interaction, the confinement and the applied static electric field affect the optical absorption. 相似文献
12.
V. N. Brudnyi D. L. Budnitskii M. A. Krivov E. A. Popova 《Russian Physics Journal》1981,24(7):663-666
The absorption spectra of n- and p-type GaAs bombarded with 2-MeV electrons at T=300K were studied in the spectral range from 0.2 eV to Eg. It was found that shallow radiation-defect levels Ec – 0.01 eV and Ec + (0.06–0.1) eV were formed. The structureless character of the absorption in the region h < Eg in electron-bombarded gallium arsenide specimens was shown to be due to the distinctive features of photoionization of deep levels and the strong electron-phonon interaction in this material.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 7, pp. 93–97, July, 1981. 相似文献
13.
The origin of spin mixing in the optical pumping cycle of F centres is investigated by measuring its wavelength dependence in the F band of KCl and KBr and the K band of KJ. 相似文献
14.
R. Kruszka M. Ekielski K. Gołaszewska K. Korwin-Mikke Z. Sidor M. Wzorek D. Pierścińska R. Sarzała T. Czyszanowski A. Piotrowska 《Opto-Electronics Review》2011,19(1):51-55
The results of modelling of the influence of photonic crystal on the performance of VCSEL-type semiconductor laser structure are shown and indicate that the use of those structures would significantly improve the working parameters of the devices. The method of fabrication of photonic crystals in the Bragg mirrors of GaAs/AlGaAs-based VCSELs is presented. 相似文献
15.
本文首次报道了采用非线性光透射技术(NLT)测量λ=2.06μm激光激发下GaAs本征半导体中三光子吸收的实验研究.观察到了三光子吸收及所伴随的自由载流子的激发态吸收,并测得了三光子吸收系数.实验测量结果与理论计算结果比较,符合较好. 相似文献
16.
Walukiewicz W Shan W Yu KM Ager JW Haller EE Miotkowski I Seong MJ Alawadhi H Ramdas AK 《Physical review letters》2000,85(7):1552-1555
We report a strongly nonlinear pressure dependence of the band gaps and large downward shifts of the conduction band edges as functions of composition in ZnS xTe (1-x) and ZnSe (y)Te (1-y) alloys. The dependencies are explained by an interaction between localized A1 symmetry states of S or Se atoms and the extended states of the ZnTe matrix. These results, combined with previous studies of III-N-V materials define a new, broad class of semiconductor alloys in which the introduction of highly electronegative atoms leads to dramatic modifications of the conduction band structure. The modifications are well described by the recently introduced band anticrossing model. 相似文献
17.
Considering two beams propagate in semiconductor crystal, this paper
discusses the polarization dependence of pump beam-induced intensity attenuation of
probe beam due to two-photon absorption (TPA). Numerical calculation
and experimental measurement demonstrate that TPA coefficient is
polarization dependent. For homogeneous materials, probe beam
attenuation arises from the imaginary part of diagonal and
off-diagonal components of third-order nonlinear susceptibilities. 相似文献
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19.
Magneto-optical absorption spectra due to exciton states and Landau-levels were measured in GaAs/AlAs multi-quantum-wells. By extrapolating the photon energies of the absorption peaks to zero magnetic field, the lowest state (1S) heavy hole exciton binding energy, EB(1S), was obtained as a function of well size Lz in the range . The Lz dependence of EBh showed the change of the exciton character from three-dimensional to two-dimensional with decreasing Lz. The diamagnetic shift observed for the heavy hole exciton peak was larger than that for the light hole exciton peak, showing the anisotropic nature of the Luttinger-Kohn Hamiltonian. The diamagnetic shift of the heavy hole exciton peak became smaller as Lz was decreased, suggesting the enhancement of the two-dimensional exciton character. 相似文献
20.
L. I. Shchepina V. M. Kostyukov S. S. Kolesnikov V. M. Kalikhman 《Optics and Spectroscopy》2002,92(4):593-595
It was found by the methods of optical spectroscopy and X-ray diffraction analysis that the N b absorption band in LiF crystals is related to the reoriented F 4 center when all the F centers lie in the (110) plane. These defects are decomposed into F 2 centers at annealing. 相似文献