Three electrons confined in multilayer quantum dots studied by the exact diagonalization method

2007

Commun. Theor. Phys.

By using the exact diagonalization method, a system of three electrons confined in a parabolic quantum dot in zero magnetic field is studied. 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 understanding the optical properties and internal electron-electron correlations of quantum dot materials.

mentioning

confidence: 99%

“…[23], we know that in some cases this favorable configuration is prohibited by symmetry. The three electrons form an ET only if the following equations are fulfilled: [23] ( e i2πL/3 − 1) = 0, (S = 3/2) ,…”

mentioning

confidence: 99%

Three-Electron Quantum Dots in Zero Magnetic Field

2007

Commun. Theor. Phys.

“…The experimental study of semiconductor QDs shows [4][5][6] that electron-electron interaction and correlation effects are of great importance in such systems. A large number of theoretical investigations [7][8][9][10][11][12] have been performed to explain the experimental observations for electronic structures and optical properties in QDs. A typical dot size is about 100 nm and each dot typically contains between 2 and 200 electrons [12].…”

Section: Introductionmentioning

confidence: 99%

Electric field effects on the intersubband optical absorptions and refractive index in double-electron quantum dots

2011

Phys. Scr.

Self Cite

The linear and nonlinear optical properties such as optical absorption and refractive index change associated with intersubband transitions in a two-electron quantum dot (QD) in the presence of an external electric field have been investigated theoretically by using the perturbation method. The exchange force, which is a strictly quantum mechanical phenomenon, has also been considered. Numerical results on typical GaAs/AlGaAs materials show that an increase of the electric field decreases the oscillator strengths, the peak positions of absorption coefficients as well as the refractive index changes. Additionally, an increase of the confinement frequency (dot size) increases (decreases) the absorption coefficients but does not significantly affect the refractive index changes. It is also observed that the intensity of the illumination and the relaxation time have drastic effects on nonlinear optical properties. Finally, we note that the optical absorption coefficients and refractive index changes of two electrons are about five times higher than that of a one-electron QD.

“…The experimental study of semiconductor QDs is expanding rapidly [3][4][5][6] and electronelectron interaction and correlation effects are shown to be of great importance [7][8][9] in such systems. In the meantime, a large number of theoretical investigations [10][11][12][13] of electronic structures and related magnetic and optical properties in QDs have been performed to explain the experimental observations. Based on a numerical solution of the Coulomb interaction between electrons, a complex groundstate behavior (singlet → triplet state transitions) as a function of a magnetic field has been predicted [8,14].…”

Section: Introductionmentioning

confidence: 99%

A study of two confined electrons using the Woods–Saxon potential

J. Phys.: Condens. Matter

2009

Self Cite

In this paper, we studied two electrons confined in a quantum dot with the Woods-Saxon potential by using the method of numerical diagonalization of the Hamiltonian matrix within the effective-mass approximation. The great advantage of our methodology is that it enables confinement regimes by varying two parameters in the model potential. A ground-state behavior (singlet [Formula: see text] triplet state transitions) as a function of the strength of a magnetic field has been investigated. We found that the confinement barrier size and the barrier inclination of a Woods-Saxon potential are important for the singlet-triplet oscillation of a two-electron quantum dot. Based on the computed energies and wavefunctions, the linear and nonlinear optical absorption coefficients have been examined between the (1)S state (L = 0) and the (1)P state (L = 1). The results are presented as a function of the incident photon energy for the different values of the barrier size and height. It is found that the optical properties of the two-electron system in a quantum dot are strongly affected by the barrier height and size.