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Makler, S. S.; Rocha, Gilmar; Anda, E. V.

doi:10.1103/physrevb.41.5857

Cited by 14 publications

(2 citation statements)

References 73 publications

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“…In addition to (3), there is a state with E = 0. The general case, which is of interest here, can be treated by mapping the many-body problem onto a single particle problem in a Fock space of higher dimension 43,44 . It is natural to consider a basis |n 1 n 2 {m ν } where n r = 0, 1 is the number of fermions on level r and m ν is the number of phonons of mode ν.…”

Section: Electron-optical-phonon Interaction: the Non-perturbativmentioning

confidence: 99%

Electron-phonon interaction effects in semiconductor quantum dots: A nonperturabative approach

2004

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Multiphonon processes in a model quantum dot (QD) containing two electronic states and several optical phonon modes are considered taking into account both intra-and inter-level terms. The Hamiltonian is exactly diagonalized including a finite number of multi-phonon processes, large enough as to guarantee that the result can be considered exact in the physically important region of energies. The physical properties are studied by calculating the electronic Green's function and the QD dielectric function. When both the intra-and inter-level interactions are included, the calculated spectra allow for explanation of several previously published experimental results obtained for spherical and self-assembled QDs, such as enhanced 2LO phonon replica in absorption spectra and up-converted photoluminescence. An explicit calculation of the spectral line shape due to intra-level interaction with a continuum of acoustic phonons is presented, where the multi-phonon processes also are shown to be important. It is pointed out that such an interaction, under certain conditions, can lead to relaxation in the otherwise stationary polaron system. PACS numbers: 78.67.De; 63.22.+m; 63.20.Kr Keywords: quantum dot, phonon, exciton, absorption, emission Rule, the broadening could be a lifetime effect owing to the electron (or exciton) transition to another state with emission or absorption of an optical phonon. However, it would require strict energy conservation in the electronphonon scattering, i.e. exact resonance between the optical phonon energy and level spacing, which should be rather accidental. This kind of argument also justified the theoretical concept of "phonon bottleneck", a very slow carrier relaxation which should be inherent to small QDs 2 . Nevertheless, an efficient phonon-mediated carrier relaxation has been reported in a number of works 21,28,30 . All these experimental results imply that multiphonon processes are important and that the e-ph interaction in QDs must be treated in a non-perturbative way, even for the moderate values of the coupling constants coming out from the calculations 31 . An important ingredient to be included is the non-adiabaticity of this interaction 2,7,22 leading to a phonon-mediated coupling of different electronic levels, even if they are separated by an energy quite different from the optical phonon energy. This is essential for understanding those experimental results which are in clear disagreement with the single level-generated Franck-Condon progression.Polaron effects in QDs have been studied theoretically in several recent papers 32,33,34,35 . The model considered in these works included two electronic levels and several Einstein phonon modes. The one-electron spectral function was obtained applying either self-consistent perturbation theory approximations 32,33 or exactly, using a combined analytical and numerical approach 34 . The results calculated using the perturbation theory approaches show shift and broadening of the levels, even for a sufficiently large detuning (defined ...

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Section: Electron-optical-phonon Interaction: the Non-perturbativmentioning

confidence: 99%

Electron-phonon interaction effects in semiconductor quantum dots: A nonperturabative approach

2004

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“…They also show that there is a charge transfer from the Ge atoms to the N atoms. There have been some studies on amorphous GeN [36] and amorphous Ge 1−x N x :H [37]. In the first one, N is considered as an impurity in a Ge cluster, and in the second the effect of the N concentration versus the widening of the gap is studied.…”

Section: Introductionmentioning

confidence: 99%