Disk-shaped Quantum Dots Research Articles

ABSORPTION SPECTRUM OF AN EXCITON IN AN InxGa1 - xAs/GaAs QUANTUM DOT IN THE PRESENCE OF A MAGNETIC FIELD

We calculate the absorption spectrum of a single exciton, confined in an In x Ga 1 - x As/GaAs disk-shaped quantum dot, as a function of the strength of an applied magnetic field. Exciton eigenstates are obtained by numerical diagonalization of the Hamiltonian, within the effective mass approximation. A correction in the expression of the Coulomb interaction matrix elements is verified.

Far-infrared giant dipole resonances in neutral quantum dots

A resonance behaviour of the far-infrared absorption probability at a frequency ∼ N 1/4 is predicted for clusters of N electron–hole pairs (2⩽ N⩽110) confined in disk-shaped quantum dots. For radially symmetric dots, the absorption is dominated by a giant dipole resonance, which accounts for more than 98% of the energy-weighted photoabsorption sum rule.

Small excitonic complexes in a disk-shaped quantum dot

Confined excitonic complexes in two dimensions, consisting of N e electrons and N h holes, are studied by means of Bethe–Goldstone equations. Systems with up to 12 pairs, and asymmetric configurations with N e≠ N h are considered. The weak confinement regime gives indication of weak binding or even unbinding in the triexciton and the four-exciton system, and binding in the higher complexes.

Negatively charged magnetoexcitons in quantum dots.

We study the interaction of an electron with an exciton in a disk-shaped quantum dot subjected to magnetic and electric fields perpendicular to the plane of the dot. The absorption spectrum of magnetoexcitons and negatively charged magnetoexcitons is calculated. The differences between neutral and negatively charged exciton spectra, as a function of the polarization of light and of the applied electric field, allow for the detection of an electron bound to an exciton in a dot.