arXiv subjects

Nguyen Hong Quang

Publications and source records attributed to Nguyen Hong Quang.

6 recordsLinked to original sources

arXiv2023

Biexciton and Quadron in Self-assembled Quantum Dots

We theoretically study biexcitons and quadrons in quantum dots with parabolic confinement and give a complete comparison between the two excitations. The calculation of quadron and biexciton binding energies as functions of electron-to-hole confinement potentials and mass ratios, using unrestricted Hartree-Fock method, shows the essential differences between biexciton and quadron. The crossover between the negative and positive binding energies is indicated. Besides, the effect of external magnetic field on the quadron and biexciton binding energies has also been investigated. In addition, the crossing between anti-binding and binding of both excited quadron and biexciton states at a certain range of the electron-to-hole oscillator length ratios has been found.

cond-mat.mes-hall↗

arXiv2021

Charged excitons or trions in 2D parabolic quantum dots?

So far in the literature the terms "charged exciton" and "trion" are often confused with each other and mostly considered as the same. In this work we show this is not the case in 2D quantum dots with a parabolic confinement. By using the unrestricted Hartree-Fock method the energy and binding energy of both charged excitons and trions in 2D parabolic quantum dots are calculated in dependence on the confinements of charge carriers in quantum dot. It is shown that the binding energies of the charged exciton and the trion behave differently in regard to the ratios of the confinements between the electron and hole. The effect of the external magnetic field on the binding energies of charged excitons has been also considered.

cond-mat.mes-hall↗

arXiv2020

Strongly confined 2D parabolic quantum dot: Biexciton or Quadron?

Excitonic systems localized in a single InAs/GaAs parabolic quantum dot are studied theoretically using an unrestricted Hartree-Fock method. The binding energies of excitons, conventional biexcitons and quadrons - four particles system of two electrons and two holes, in the ground state have been obtained as functions of magnetic field and confinement potential. It is found that for strong confinement, while the binding energy of biexciton is negative, the binding energy of quadron is positive, suggesting the strong lateral confinement of the parabolic quantum dot supports the formation of a quadron rather than a biexciton.

cond-mat.mes-hall↗

arXiv2003

Exact calculation of single-electron states in Si-nanocrystal embedded in SiO2

We present an exact calculation of the single-electron energies and wave-functions for any bound state in a realistic Si-SiO2 spherical quantum dot, including the material dependence of the electron effective mass. The influence of dot radius, confinement barrier potential and barrier-to-dot electron mass ratio on the electronic structure is investigated in detail. The results show that the energy structure shifts down from some tens to some hundreds meV compared to that obtained in the simplified model where the change in effective mass is neglected. Our exact single-electron calculation is finally used to verify the accuracy of the results obtained from a numerical approximate method developed to treat many-electron systems.

cond-mat.mtrl-sci↗

arXiv1995

Density-dependent phonoriton states in highly excited semiconductors

The dynamical aspects of the phonoriton state in highly-photoexcited semiconductors is studied theoretically. The effect of the exciton-exciton interaction and nonbosonic character of high-density excitons are taken into account. Using Green's function method and within the Random Phase Approximation it is shown that the phonoriton dispersion and damping are very sensitive to the exciton density, characterizing the excitation degree of semiconductors.

cond-mat↗

arXiv1995

Density-Dependent Squeezing of Excitons in Highly Excited Semiconductors

The time evolution from coherent states to squeezed states of high density excitons is studied theoretically based on the boson formalism and within the Random Phase Approximation. Both the mutual interaction between excitons and the anharmonic exciton-photon interaction due to phase-space filling of excitons are included in consideration. It is shown that the exciton squeezing depends strongly on the exciton density in semiconductors and becomes smaller with increasing the latter.

cond-mat↗