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151.
Kouichi Akahane Naokatsu Yamamoto Naoki Ohtani 《Physica E: Low-dimensional Systems and Nanostructures》2004,21(2-4):295
We fabricated InAs quantum dots (QDs) with a GaAsSb strain-reducing layer (SRL) on a GaAs(0 0 1) substrate. The wavelength of emission from InAs QD is shown to be controllable by changing the composition and thickness of the SRL. An increase in photoluminescence intensity with increasing compositions of Sb and thickness of the GaAsSb SRL is also seen. The efficiency of radiative recombination was improved under both conditions because the InAs/GaAsSb/GaAs hetero-interface band structure more effectively suppressed carrier escape from the InAs QDs. 相似文献
152.
Effect of the dielectric-constant mismatch and magnetic field on the binding energy of hydrogenic impurities in a spherical quantum dot 总被引:1,自引:0,他引:1
Aram Kh. Manaselyan Albert A. Kirakosyan 《Physica E: Low-dimensional Systems and Nanostructures》2004,22(4):825-832
Within the effective mass approximation and variational method the effect of dielectric constant mismatch between the size-quantized semiconductor sphere, coating and surrounding environment on impurity binding energy in both the absence and presence of a magnetic field is considered. The dependences of the binding energy of a hydrogenic on-center impurity on the sphere and coating radii, alloy concentration, dielectric-constant mismatch, and magnetic field intensity are found for the GaAs–Ga1−xAlxAs–AlAs (or vacuum) system. 相似文献
153.
154.
S. H. Park J. H. Chang M. Yang H. S. Ahn S. N. Yi K. Goto M. W. Cho T. Yao J. S. Song 《Current Applied Physics》2004,4(6):607-610
Photoluminescence (PL) linewidth broadening of CdxZn1 − xSe/ZnSe triple quantum wells, grown on GaAs substrates by molecular beam epitaxy (MBE), has been investigated. Various quantum well (QW) samples have been prepared with different QW thickness and composition (Cd-composition). Measured and calculated PL linewidth are compared. Both composition and thickness fluctuations are considered for the calculation with the parameters such as the volume of exciton, nominal thickness and composition of QWs. Surface roughness measured by atomic force microscopy (AFM) is used to estimate the interface roughness. Results show that when Cd-composition increases additional linewidth broadening due to Zn/Cd interdiffusion is enhanced. 相似文献
155.
Xin Lu Jing Wang Chang-Qin Wu 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,49(3):325-331
Phonon effects in tunnelling through a double quantum dot molecule
are investigated by use of a recently developed technique, which
is based on an exact mapping of a many-body electron-phonon
interaction problem onto a multichannel one-body problem. The
molecule is sandwiched between two ideal electrodes and the
electron at each dot of the molecule interacts independently with
Einstein phonons. Single-electron transmission rates through the
molecule are computed and the nonlinear spectrum obtained shows a
structure with many more satellite peaks due to the excitations of
phonons. The strength of resonant peaks is found to be strongly
dependent on the number of excited phonons. The effects of
electron-phonon interaction on the current and shot noise,
depending on the voltage bias applied at the two electrodes as
well as the potential energy of the molecule, are discussed. 相似文献
156.
In this work we investigate the influence of the combined effect from random self-affine roughness, finite conductivity, and finite temperature on the pull-in voltage in microswitches influenced by thermal and quantum vacuum fluctuations through the Casimir force and electrostatic forces. It is shown that for separations within the micron or sub-micron range the roughness influence plays a dominant role, while temperature starts to show its influence well above micron separations. Indeed, increasing the temperature leads to higher pull-in voltages since it leads to an increased Casimir force. The temperature influence is more significant for relatively large roughness exponent H ∼ 1, while its influence is significantly lower with increasing lateral roughness correlation length ξ or due to long wavelength surface smoothness. 相似文献
157.
X.S. Cai 《Applied Surface Science》2006,252(8):2776-2781
SiGe/Si quantum wells (QWs) with different Boron doping concentrations were grown by molecular beam epitaxy (MBE) on p-type Si(1 0 0) substrate. The activation energies of the heavily holes in ground states of QWs, which correspond to the energy differences between the heavy hole ground states and Si valence band, were measured by admittance spectroscopy. It is found that the activation energy in a heavily doped QW increases with doping concentration, which can be understood by the band alignment changes due to the doping in the QWs. Also, it is found that the activation energy in a QW with a doping concentration of 2 × 1020 cm−3 becomes larger after annealing at a temperature of 685 °C, which is attributed to more Boron atoms activation in the QW by annealing. 相似文献
158.
We present a quantum protocol for the solution of a two-party comparison task with the help of a semi-honest third party, which can be used to solve the millionaire problem. The secrets are coded into the phases of d-level entangled states by local operations and read by the third party's collective measurements. The two parties can deduce the results of comparisons based on the secret bits shared between them beforehand and the announcement of the third party. Moreover, others will learn no information of the comparison results, even the third party. Our scheme is private and fair, and the security has also been discussed. 相似文献
159.
We quantitatively estimate the effect of spontaneous Raman scattering on a quantum channel wavelength-multiplexed with a classical channel. Based on an experiment that measured the generation power of spontaneous Raman scattering in a fiber, the performance of wavelength-multiplexed quantum key distribution (QKD) systems using the differential-phase-shift protocol is evaluated for various system conditions. 相似文献
160.
F. Ungan 《Journal of luminescence》2011,131(11):2237-2243
In the present work, the changes in the intersubband optical absorption coefficients and the refractive index in a modulation-doped quantum well have been investigated theoretically. Within the envelope function approach and the effective mass approximation, the electronic structure of the quantum well is calculated from the self-consistent numerical solution of the coupled Schrödinger-Poisson equations. The analytical expressions of optical properties are obtained by using the compact density-matrix approach. The numerical results GaAs/AlxGa1−xAs are presented for typical modulation-doped quantum well system. The linear, third-order nonlinear and total absorption and refractive index changes depending on the doping concentration are investigated as a function of the incident optical intensity and structure parameters, such as quantum well width and stoichiometric ratio. The results show that the doping concentration, the structure parameters and the incident optical intensity have a great effect on the optical characteristics of these structures. 相似文献