Donor centers and absorption spectra in quantum dots

Abstract

We have studied the electronic properties and optical absorption spectra of three different cases of donor centers, D 0 , D − and D 2− , which are subjected to a perpendicular magnetic field, using the exact diagonalization method. The energies of the lowest lying states are obtained as function of the applied magnetic field strength B and the distance ζ between the positive ion and the confinement xy-plane. Our calculations indicate that the positive ion induces transitions in the ground-state, which can be observed clearly in the absorption spectra, but as ζ → 0 the strength of the applied magnetic field needed for a transition to occur tends to infinity.

Charged donors in quantum dots: Finite difference and fractional dimensions results

“…In the past decade, there has been increasing interest in the properties of negatively charged donors (D − centers) in quasi-two-dimensional (2D) systems, particularly in quantum wells (QWs) [1][2][3][4][5][6][7][8][9][10][11][12][13] and in quantum dots (QDs). 14,15 The D − centers can be formed in bulk semiconductors only under metastable conditions, 2 however, in semiconductor heterostructures these are readily formed because of the dramatic increase of the D − binding energy as a consequence of the spatial confinement, which is even further increased by the application of a magnetic field. Different theoretical approaches have been used to calculate the spectra of D − systems in QWs and QDs, such as the diffusion quantum Monte Carlo method, 3,4 the finite difference technique, 12 and the variational method.…”

“…8,9 Recently, D − systems have been studied in quantum dots. In particular, the problem of the neutral and charged donor in a parabolic 2D quantum dot were studied, 14,15 both in the case when the donor is lying in the confinement plane and when it is displaced outside the plane.…”

Far-infrared spectra of lateral quantum dot molecules

“…Also calculations [9,10,11,12,13,14,15,16] have shown non-trivial FIR spectra of nonparabolic QDs. It is also possible that spin-orbit interaction [17] and impurities near quantum dots [18] can have an effect on the FIR spectrum. In a nonparabolic QD, the relative internal motion of electrons could be accessible with the FIR spectroscopy, but recent studies suggest that additional features in the FIR spectra are still of collective nature [9].…”