Electronic and optical properties of strained quantum dots modeled by 8-band k⋅p theory

Stier, O.; Grundmann, Marius; Bimberg, D.

doi:10.1103/physrevb.59.5688

Cited by 1,069 publications

(815 citation statements)

References 63 publications

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“…Thus, we are not considering tunneling of states, which have a lower energy than the conduction-band edge of the ''barrier'' material, as in vertically coupled dots, but tunneling at energies that are lower energy than those of isolated WL states, but still lie well above the conduction-band edge. A third and crucial difference is that here we are not discussing the coupling of the ground state, but of the excited states, whose lateral extent is typically between 1.5 and 2 times that of the ground state, 20,30 and was recently calculated to be about 66% more extended in isolated InAs/ InP QDs grown on a ͑311͒B substrate. 31 We can also compare the wave-function penetration in the two cases.…”

Section: B Discussionmentioning

confidence: 99%

Increase of charge-carrier redistribution efficiency in a laterally organized superlattice of coupled quantum dots

et al. 2006

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We report the observation of enhanced charge-carrier redistribution in laterally organized and coupled InAs/ InP quantum dots ͑QDs͒. We show that a periodic organization appears in the QD plane for a high in-plane QD density ͑QDD͒. This organization enhances the lateral coupling between the dots, which is evidenced by photoluminescence and magnetophotoluminescence experiments. Electronic inter-QD lateral coupling results in an improved charge-carrier distribution at low temperature, as shown by electroluminescence on high QDD QD lasers. We conclude that the inter-QD tunneling occurs via the tunneling of excited states through the wetting layer, and discuss the prospects of using coupled QDs for improving the quantum efficiency and dynamical properties of QD lasers.

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Section: B Discussionmentioning

confidence: 99%

Increase of charge-carrier redistribution efficiency in a laterally organized superlattice of coupled quantum dots

et al. 2006

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“…Due to the computational complexity of the pseudopotential methods that take into account the atomistic nature of the structure, one often employs the k · p method which is considered to be a reliable tool for modeling the electronic structure of quantum dots despite its known limitations 8 . The symmetry of the k · p model itself is the symmetry group of the zincblende crystal lattice.…”

Section: Introductionmentioning

confidence: 99%

“…Since the pyramid shape symmetry group is a subgroup of the symmetry of the zincblende crystal lattice, it follows that the symmetry group of the model is the double C 4 group 17 . Two different approaches are used to calculate the strain distribution in quantum dots -the continuum mechanical 8,11 and the valence force field model 8,10 . When the strain distribution is incorporated in the k · p method, the continuum mechanical model preserves the C 4 symmetry, while the valence force field model, due to its atomistic nature, breaks it 8,10 .…”

Section: Introductionmentioning

confidence: 99%

“…Two different approaches are used to calculate the strain distribution in quantum dots -the continuum mechanical 8,11 and the valence force field model 8,10 . When the strain distribution is incorporated in the k · p method, the continuum mechanical model preserves the C 4 symmetry, while the valence force field model, due to its atomistic nature, breaks it 8,10 . Nevertheless, the comparisons of the two models have shown that they give similar results 8,18 .…”

Section: Introductionmentioning

confidence: 99%

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Symmetry ofk∙pHamiltonian in pyramidalInAs∕GaAsquantum dots: Application to the

et al. 2005

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A method for the calculation of the electronic structure of pyramidal self-assembled InAs/GaAs quantum dots is presented. The method is based on exploiting the C 4 symmetry of the 8-band k · p Hamiltonian with the strain taken into account via the continuum mechanical model. The operators representing symmetry group elements were represented in the plane wave basis and the group projectors were used to find the symmetry adapted basis in which the corresponding Hamiltonian matrix is block diagonal with four blocks of approximately equal size. The quantum number of total quasi-angular momentum is introduced and the states are classified according to its value. Selection rules for interaction with electromagnetic field in the dipole approximation are derived. The method was applied to calculate electron and hole quasibound states in a periodic array of vertically stacked pyramidal self-assembled InAs/GaAs quantum dots for different values of the distance between the dots and external axial magnetic field. As the distance between the dots in an array is varied, an interesting effect of simultaneous change of ground hole state symmetry, type and the sign of miniband effective mass is predicted. This effect is explained in terms of the change of biaxial strain. It is also found that the magnetic field splitting of Kramer's double degenerate states is most prominent for the first and second excited state in the conduction band and that the magnetic field can both separate otherwise overlapping minibands and concatenate otherwise nonoverlapping minibands.

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“…Piezoelectric potentials, however, caused by shear strain from the lattice mismatch between InAs and GaAs, tend to elongate the hole in the ͓110͔ direction, and the electron in the ͓110͔ direction. 24 Thus for strongly confined states, shear strain tends to also elongate the exciton in the ͓110͔ direction, since the extent of the exciton wave function is dominated by the small hole. However, as confinement is reduced, shape asymmetry becomes less dominant as the electron and hole states extend into the barrier, and the relative size and elongation of the electron and hole states could potentially lead to an exciton state elongated along ͓110͔, the preferred axis of expansion for the electron.…”

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confidence: 99%

Inversion of exciton level splitting in quantum dots

et al. 2005

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The demonstration of degeneracy of the exciton spin states is an important step towards the production of entangled photons pairs from the biexciton cascade. We measure the fine structure of exciton and biexciton states for a large number of single InAs quantum dots in a GaAs matrix; the energetic splitting of the horizontally and vertically polarised components of the exciton doublet is shown to decrease as the exciton confinement decreases, crucially passing through zero and changing sign. Thermal annealing is shown to reduce the exciton confinement, thereby increasing the number of dots with splitting close to zero.Comment: 12 pages, 4 figure

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Electronic and optical properties of strained quantum dots modeled by 8-band k⋅p theory

Cited by 1,069 publications

References 63 publications

Increase of charge-carrier redistribution efficiency in a laterally organized superlattice of coupled quantum dots

Increase of charge-carrier redistribution efficiency in a laterally organized superlattice of coupled quantum dots

Symmetry ofk∙pHamiltonian in pyramidalInAs∕GaAsquantum dots: Application to the

Inversion of exciton level splitting in quantum dots

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