共查询到20条相似文献,搜索用时 78 毫秒
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《Superlattices and Microstructures》1996,19(2):137-149
The binding energy of the ground state of a hydrogenic off-center donor in a spherical quantum dot under a parabolic potential is calculated by a variational method within the effective-mass approximation. The parabolic potential is assumed to be a spherically symmetric potential. The location effects of a hydrogenic donor under a parabolic potential on the binding energy of the ground state are studied. It is found that in the case of an on-center donor, the parabolic potential tends to enhance the strength of the Coulomb interaction and the binding energy of the ground state, and in the case of an off-center donor, the effect of the parabolic potential on the binding energy of the ground state is somewhat complicated. 相似文献
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《Superlattices and Microstructures》2001,29(3):233-238
A wavefunction is proposed for calculating the ground-state energy of a screened donor in a spherical quantum dot under a parabolic potential by a variational method. The donor is taken to be at the center of the quantum dot. Results are presented for four values of the screening parameter by the proposed wavefunction as well as for the hydrogenic donor case by a wavefunction used by Xiao et al.. To assess the accuracy of the results, ‘exact’ energies are also obtained by numerical integration of the Schrödinger equation. It is shown that the proposed wavefunction gives very good results in all cases including the hydrogenic donor case. 相似文献
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C. Dane H. Akbas A. Guleroglu S. Minez K. Kasapo?lu 《Physica E: Low-dimensional Systems and Nanostructures》2011,44(1):186-189
A theoretical study of combined effects of the hydrostatic pressure and the electric field on the subband ground state energy and on the normalized ground state binding energy of a hydrogenic donor impurity on center located in a GaAs/AlAs spherical quantum dot with fixed dot radius is presented. The study is performed in the framework of the effective mass and parabolic band approximations and using a variational procedure. As a key result, it may be possible to gather high resolution maps of electric field on the studied structure with described technique. 相似文献
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柱形量子点中弱耦合磁极化子的性质 总被引:3,自引:3,他引:0
应用线性组合算符方法和幺正变换方法,研究在抛物势作用下的柱形量子点中磁极化子的性质。对ZnS量子点的数值计算表明,量子点中磁极化子的基态能量随特征频率、回旋共振频率的增大而增加,这是由于特征频率增加时振动能量、回旋共振频率增加时外磁场中的附加能量增加所致。当特征频率(或回旋共振频率)增加到某一值时,磁极化子能量由负变为正。基态能量随柱高的减小而增加,且柱高越小,增加越快;当柱高减小到某一值时,磁极化子能量也由负变为正。总之,柱形量子点中的磁极化子,其基态能量与量子点的尺度、外磁场、特征频率等有关。 相似文献
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XIE Wen-Fang 《理论物理通讯》2001,36(5):631-634
Binding energiesfor an exciton (X) trapped in the two-dimensional quantum dot by a negative ion located on the z axis at a distance from the dot plane are calculated by using the method of few-body physics.This configuration is called a barrier (A-,X) center.The dependence of the binding energy of the ground state of the barrier (A-,X)center on the electron-to-hole mass ratio for a few values of the distance d between the fixed negative ion on the z axis and the dot plane is obtained.We find that when d → 0,the barrier (A-,X) center has not any bound state.We also studied the stability and binding energy of the ground state of the barrier (A-,X) center in a parabolic quantum dot as a function of the distance d between the fixed negative ion on the z axis and the dot plane. 相似文献
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XIE Wen-Fang 《理论物理通讯》2007,47(1):167-170
We study a neutral donor center (D^0) and a negatively charged donor center (D^-) trapped by a quantum dot, which is subjected to a Gaussian potential confinement. Calculations are made by using the method of numerical diagonalization of Hamiltonian within the effective-mass approximation. The dependence of the ground state of the neutral shallow donor and the negatively charged donor on the dot size and the potential depth is investigated. The same calculations performed with the parabolic approximation of the Gaussian potential lead to the results that are qualitatively and quantitatively different from each other. 相似文献
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XIEWen-Fang 《理论物理通讯》2001,35(4):497-500
We investigate the effect of the position of the donor in quantum dots on the energy spectrum in the presence of a perpendicular magnetic field by using the method of few-body physics,As a function of the magnetic field,we find,when D^- centers are placed sufficiently off-center,discontinuous ground-state transitions which are similar to those found in many-electron parabolic quantum dots.Series of magic numbers of angular momentum which minimize the ground-state electron-electron interaction energy have been discovered.The dependence of the binding energy of the gound-state of the D^- center on the dot radius for a few values of the magnetic field strength is obtained and compared with other results. 相似文献
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Effects of Electric Field on Electronic States in a GaAs/GaAlAs Quantum Dot with Different Confinements 下载免费PDF全文
Binding energies of shallow hydrogenic impurity in a GaAs/GaAlAs quantum dot with spherical confinement, parabolic confinement and rectangular confinement are calculated as a function of dot radius in the influence of electric field. The binding energy is calculated following a variational procedure within the effective mass approximation along with the spatial depended dielectric function. A finite confining potential well with depth is determined by the discontinuity of the band gap in the quantum dot and the cladding. It is found that the contribution of spatially dependent screening effects are small for a donor impurity and it is concluded that the rectangulax confinement is better than the parabolic and spherical confinements. These results are compared with the existing literature. 相似文献
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Effect of the Electron—Phonon Coupling on Barrier D^— Quantum Dots in Magnetic Fields 总被引:2,自引:0,他引:2
XIEWen-Fang 《理论物理通讯》2002,37(1):99-104
The influence of the electron-phonon coupling of the energy of low-lying states of the barrier D^- center,which consists of a positive ion located on the z-azis at a distance from the two-dimensional quantum dot plane and two electrons in the dot plane bound by the ion,is investigated at arbitrary strength of maguetic field by mading use of the method of few-body physics.Discontinuous ground-state energy transitions induced by the magnetic field are reported.The dependence of the binding energy of the D^- ground state on the quantum dot radius is obtained.A considerable enhancement of the binding is found for the D^- ground state,which results from the confinement of electrons and electron-phonon coupling. 相似文献
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F. Dujardin E. Feddi E. Assaid A. Oukerroum 《The European Physical Journal B - Condensed Matter and Complex Systems》2010,74(4):507-516
The effect of an electric field on the ground state energy of an exciton bound to an ionized donor (D+, X) was studied in CdSe spherical quantum dots where quantum confinement is described by an infinitly deep potential. Calculations
have been performed in the framework of the effective mass approximation using a variational method by choosing an appropriate
sixty-terms wave function taking into account different interparticles correlations and symetry distorsion induced by the
electric field. It appears that the Stark shift is significant even for low fields and depends strongly of spherical dot sizes.
The competition between the confinement effect and the Stark effect is discussed as function of the spherical dot size and
the applied electric field strength. The (D+, X) Stark shift is estimated and its behavior is discussed as a function of the dot radius and electric field strength. The
electron and hole average distances have also been calculated and the role of the ionized donor in the excitonic dissociation
is established. 相似文献
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抛物量子点中弱耦合磁极化子的性质 总被引:12,自引:7,他引:5
应用线性组合算符和幺正变换方法研究了抛物量子点中磁极化子的基态性质。得出基态能和基态束缚能随有效束缚强度增大而减小,随回旋频率增大而增大。当有效柬缚强度给定,基态能量随电子-体纵光学声子耦合强度增加而减小。当有效束缚强度l0>0.3时,电子-体纵光学声子耦合强度的变化对量子点中弱耦合磁极化子的基态能量的影响变得显著。当有效束缚强度l0<0.3时,电子-体纵光学声子耦合强度的变化对基态能量影响很小。由于有效束缚强度与量子点受限强度的平方根成反比,所以量子点受限越强,基态能量、基态束缚能越大,电子一体纵光学声子耦合强度和磁场的变化对量子点的影响相对越小;当量子点受限变弱时,电子-声子耦合强度变化对量子点的影响变大,磁场对量子点的影响也变大,所以在量子点中,极化子对量子点的影响不容忽略。 相似文献
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A three-electron quantum dot under an external magnetic field was studied. A number of phase diagrams have been obtained to demonstrate how the variation of the magnetic field and/or the parameters of confinement would lead to the occurrence of doublet–quadruplet transitions. Both the confinement with parabolic potential and the square well potential have been considered. We show that the parameters of confinement alter the ground state of the quantum dot from a spin doublet to a spin quadruplet. This result indicates that the quantum dot can be used as a good candidate for qubit of a quantum computer. 相似文献
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研究了抛物量子点中弱耦合束缚极化子的性质,采用改进的线性组合算符和幺正变换方法导出了束缚极化子的振动频率、有效质量和相互作用能。讨论了量子点的有效受限长度、电子LO声子耦合强度和库仑场对抛物量子点中弱耦合极化子的振动频率、有效质量和相互作用能的影响。数值计算结果表明:弱耦合束缚极化子的振动频率和相互作用能随有效受限长度的减少而急剧增大,振动频率随库仑势以及电子LO声子耦合强度的增加而增加,而相互作用能随库仑势以及电子LO声子耦合强度的增加而减小。有效质量仅与电子LO声子耦合强度有关。 相似文献