K. L. Janssens

Strain and band edges in single and coupled cylindrical InAs/GaAs and InP/InGaP self-assembled quantum dots

A comparative study is made of the strain distribution in cylindrical InAs/GaAs and InP/InGaP self-assembled quantum dots as obtained from isotropic elasticity theory, the anisotropic continuum mechanical model, and from atomistic calculations. For the isotropic case, the recently proposed approach [J. H. Davies, J. Appl. Phys. 84, 1358 (1998)] is used, while the finite-element method, the valence force field method, and Stillinger–Weber potentials are employed to calculate the strain in anisotropic structures. We found that all four methods result in strain distributions of similar shapes, but with notable quantitative differences inside the dot and near the disk–matrix boundary. The variations of the diagonal strains with the height of the quantum dot, with fixed radius, as calculated from all models, are almost linear. Furthermore, the energies of the band edges in the two types of quantum dots are extracted from the multiband effective-mass theory by inserting the strain distributions as obtained by t...

Stark shift in single and vertically coupled type-I and type-II quantum dots

We theoretically studied the Stark effect on an exciton in single and vertically coupled type-I and type-II quantum dots. Only for the single type-I dot does the exciton energy show a parabolic dependence on the applied field. A dipole moment is induced by the applied electric field for vertically coupled type-I dots and for type-II dots, leading to a linear dependence of the Stark shift on the electric field. Furthermore, we predict that spontaneous symmetry breaking can occur for vertically coupled type-II dots leading to a permanent dipole moment.

Single and vertically coupled type-II quantum dots in a perpendicular magnetic field: Exciton ground-state properties

The properties of an exciton in a type-II quantum dot are studied under the influence of a perpendicular applied magnetic field. The dot is modeled by a quantum disk with radius R, thickness d and the electron is confined in the disk, whereas the hole is located in the barrier. The exciton energy and wave functions are calculated applying a self-consistent mean-field theory in the Hartree approximation using a finite difference mesh method. We distinguish two different regimes, namely,

Electron and hole localization in coupled InP/InGaP self-assembled quantum dots

d\ensuremath{\ll}2R

Hole Band Engineering in Self-Assembled Quantum Dots and Molecules

(the hole is located above and below the disk) and

Excitons in Single and Vertically Coupled Type II Quantum Dots in High Magnetic Fields

d\ensuremath{\gg}2R

Magneto‐Exciton in Single and Coupled Type II Quantum Dots

(the hole is located at the radial boundary of the disk), for which angular momentum (l) transitions are predicted with increasing magnetic field. We also considered a system of two vertically coupled dots where now an extra parameter is introduced, namely, the interdot distance

Effect of isotropic versus anisotropic elasticity on the electronic structure of cylindrical InP/In_{0.49}Ga_{0.51}P self-assembled quantum dots

{d}_{z}.

Magnetoexcitons in planar type-II quantum dots in a perpendicular magnetic field

For a sufficient large magnetic field, each

Effect of strain on the magnetoexciton ground state inInP/GaxIn1−xPquantum disks

{l}_{h}