Exciton and negative trion dissociation by an external electric field in vertically coupled quantum dots

Abstract

We study the Stark effect for an exciton confined in a pair of vertically coupled quantum dots. A single-band approximation for the hole and a parabolic lateral confinement potential are adopted which allows for the separation of the lateral center-of-mass motion and consequently for an exact numerical solution of the Schrödinger equation. We show that for intermediate tunnel coupling the external electric field leads to the dissociation of the exciton via an avoided crossing of bright and dark exciton energy levels which results in an atypical form of the Stark shift. The electric-field-induced dissociation of the negative trion is studied using the approximation of frozen lateral degrees of freedom. It is shown that in a symmetric system of coupled dots the trion is more stable against dissociation than the exciton. For an asymmetric system of coupled dots the trion dissociation is accompanied by a positive curvature of the recombination energy line as a function of the electric field.

PRB - in print

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• Exciton spectra in vertical stacks of triple and quadruple quantum dots in an electric field
• Excitons in quantum dot molecules: Coulomb coupling, spin-orbit effects and phonon-induced line broadening
• Interplay of coupling and superradiant emmision in the optical response of a double quantum dot
• Vacuum-induced coherence in quantum dot systems
• Phonon effects on the radiative recombination of excitons in double quantum dots
• Forster energy transfer signatures in optically driven quantum dot molecules
• Understanding electric field control of electronic and optical properties of strongly-coupled multi-layer quantum dot molecules
• Dike states in multiple quantum dots
• Decay and persistence of spatial coherence during phonon-assisted relaxation in double quantum dots
• Trions and biexcitons in a nanowire
• Polaron resonances in two vertically stacked quantum dots
• Fine-structure splitting of exciton states in quantum dot molecules: symmetry and tunnel-coupling effects