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Binding Energy of an Exciton Bound to Ionized Acceptor in Quantum Dots

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Communications in Theoretical Physics 2001年第11期36卷 631-634页

作者： XIE wen-fang Department of Physics Guangzhou UniversityGuangzhou 510405China

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 *** configuration is called a barrier (A-,X) *** 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 *** find that when d → 0,the barrier (A-,X) center has not any bound *** 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.

关键词： quantum dot,exciton complex,few-body physics

Donor Centers in a Gaussian Potential

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Communications in Theoretical Physics 2007年第1期47卷 167-170页

作者： XIE wen-fang Department of Physics Guangzhou University Guangzhou 510006 China

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.

关键词： donor quantum dots

A Negative Donor Center Trapped by a Spherical Quantum Dot

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Communications in Theoretical Physics 2008年第2期49卷 507-510页

作者： XIE wen-fang Department of Physics Guangzhou University Guangzhou 510006 China

The properties of the low-lying states of a negative donor center trapped by a spherical quantum dot, which is subjected to a parabolic potential confinement, are investigated in the absence of magnetic field. The calculations have been performed by means of the exact diagonalization of the Hamiltonian matrix within the effective-mass approximation. We find that there is only one bound state the D^- center in a spherical parabolic quantum dot in the absence of magnetic field. The binding energy of the ground state is obtained as a function of the dot size. Moreover, the critical confined potential radius value at which the negative donor center changes from unbound to bound is obtained.

关键词： quantum dots donor

Binding Energy of Excitons in a Quantum Ring

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Communications in Theoretical Physics 2008年第8期50卷 529-531页

作者： XIE wen-fang Department of Physics Guangzhou University Guangzhou 510006 China

The binding energy of excitons confined to a quantum ring under the influence of perpendicular homogeneous magnetic field is calculated as a function of the ring radius. Calculations are made by using the method of exact diagonalization within the effective-mass approximation. The feature of binding energy of the ground state as a function of the ring radius for several values of the magnetic field has been revealed. The interesting feature of our study is that, in a quantum ring, the geometric structure of exeitons may reveal transition.

关键词： quantum ring exciton

Ground State Transitions of Four-Electron Quantum Dots in Zero Magnetic Field

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Communications in Theoretical Physics 2008年第3期49卷 763-766页

作者： XIE wen-fang Department of Physics Guangzhou University Guangzhou 510006 China

In this paper, we study four electrons confined in a parabolic quantum dot in the absence of magnetic field, by the exact diagonalization method. The ground-state electronic structures and orbital and spin angular momenta transitions as a function of the confined strength are investigated. We find that the confinement may cause accidental degeneracies between levels with different low-lying states and the inversion of the energy values. The present results are useful to understand the optical properties and internal electron-electron correlations of quantum dot materials.

关键词： electron-electron interaction quantum dot semiconductor

A Two-Electron Quantum Ring Under Magnetic Fields

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Communications in Theoretical Physics 2008年第6期49卷 1619-1621页

作者： XIE wen-fang Department of Physics Guangzhou University Guangzhou 510006 China

We calculate the energy levels of low-lying states of a two-electron quantum ring under the influence of perpendicular homogeneous magnetic field. Calculations are made by using the method of exact diagonalization within the effective-mass approximation. The ground-state electronic structures and angular momentum transitions as a function of the strength of a magnetic field have been revealed.

关键词： electron-electron interaction quantum dot semiconductor

Feature of a Confined Positronium Negative Ion by a Spherical Parabolic Potential

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Communications in Theoretical Physics 2007年第3期47卷 547-549页

作者： XIE wen-fang Department of Physics Guangzhou University Guangzhou 510006 China

The ground and three low-excited states of the positronium negative ion Confined by a spherical harmonic oscillator potential are studied employing the adiabatic hyperspherical approach method. Total energies are obtained as a function of the confined potential radii. We find that the confinement may cause accidental degeneracies between levels with different low-excited states and the inversion of the energy wlues.

关键词： positronium negative ion energy spectrum

Linear and Nonlinear Optical Absorptions of a Hydrogenic Donor in a Quantum Dot Under a Magnetic Field

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Communications in Theoretical Physics 2009年第5期51卷 923-926页

作者： XIE wen-fang School of Physics and Electronic Engineering Guangzhou University Guangzhou 510006 China

The linear and nonlinear optical properties of a hydrogenic donor in a disc-like parabolic quantum dot in the presence of an external magnetic field are studied. The calculations were performed within the effective mass approximation, using the matrix diagonalization method and the compact density-matrix approach. The linear and nonlinear optical absorption coefficients between the ground （L =0） and the first excited state （L = 1） have been examined based on the computed energies and wave functions. We find that the linear, nonlinear third-order, and total optical absorption coefficients are strongly affected by the confinement strength of QDs, the external magnetic field, and the incident optical intensity.

关键词： quantum dot nonlinear optics

Linear and Nonlinear Optical Absorptions of a Donor Impurity in Spherical Quantum Dots

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Communications in Theoretical Physics 2009年第7期52卷 155-158页

作者： XIE wen-fang School of Physics and Electronic Engineering Guangzhou University Guangzhou 510006 China

An investigation of the optical properties of a hydrogenic donor in spherical parabolic quantum dots hasbeen performed by using the matrix diagonalization *** optical absorption coefficient between the ground(L=0) and the first excited state (L=1) have been examined based on the computed energies and wave *** results are presented as a function of the incident photon energy for the different values of the confinement *** results show the effects of the quantum size and the impurity on the optical absorption coefficient of a donorimpurity quantum dot.

关键词： quantum dot optical absorption