Local Optical Absorption by Confined Excitons in Single and Coupled Quantum Dots

Abstract

We study theoretically the local absorption spectra of single and double semiconductor quantum dots, where the three-dimensional confinement leads to an enhancement of Coulomb effects. We show that because of such Coulomb correlations the intensity of certain optical peaks as a function of the resolution can exhibit an unexpected non-monotonic behavior for spatial resolutions comparable with the excitonic Bohr radius.

Magnetic field effects on the near field spectra of quantum dots

“…It has been theoretically predicted that the Coulomb interaction and the spatial interference of the exciton wavefunctions induce unexpected features to the linear near field spectra of single and coupled semiconductor quantum dots (QDs) [1,2]. Specifically, when the spatial resolution is close to the excitonic Bohr radius, r , the intensity of these spectral features depends on the spatial resolution in a remarkably nonmonotonic way [1,2]. For GaAs, 12 r ª nm and since the (undisputable) spatial resolution achieved at that time was ª 100-200 nm, no direct comparison between theory and experiment could be made.…”

“…Luckily, there exist some, and especially InAs ( 38 r ª nm) is a very commonly used semiconductor. (2) The spatial resolution of the near-field probes had to be sharpened. (3) The experimental set-up could be improved by decreasing the surface cap layer which causes 50 -100 nm undesirable spacing between the QD and the aperture of the near field probe.…”