Berlin 2012 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 37: Quantum Dots and Wires: Optical Properties I (mainly InGaAs Dots)
HL 37.7: Vortrag
Dienstag, 27. März 2012, 12:15–12:30, ER 164
Tight binding model of strain-reducing layers in semiconductor quantum dots — •Elias Goldmann, Stefan Barthel, Kolja Schuh, Gerd Czycholl, and Frank Jahnke — Institute of theoretical physics, Universit of Bremen
In recent years, semiconductor quantum dots have been the subject of intense research. Especially the excitonic fine-structure splitting (FSS) has received much attention due to its influence on the photon pair entanglement of the quantum dot biexciton emission.
We present results of an atomistic empirical tight-binding model (ETB) for the calculation of electronic properties of semiconductor nanostructures. We choose a sp3s* basis localized at each atomic site and include next-neighbour-interaction as well as spin-orbit-coupling. The influence of lattice-mismatch induced strain is accounted for on an atomistic scale via the valence-force-field method using the Keating potential. An implementation of the Krylov-Schur algorithm with harmonic extraction in SLEPc [1] is used to compute the interior eigenstates and eigenenergies of the resulting TB-Hamiltonian.
We use the calculated eigenstates as an input for a full configuration interaction treatment to compute the FSS.
Within this ETB model we investigate the electronic properties of lens- and trapezoid-shaped self-assembled InGaAs quantum dots in a InGaAs strain-reducing layer [2], embedded in a GaAs matrix and located on top a wetting layer. The influences of dot shape and Indium-concentration on the confined electronic states and optical transitions are presented.
[1] V. Hernandez et al., ACM. Trans. Math. Software: 31 351 (2005)
[2] A. Amtout et al., J. Appl. Phys. 96 3782 (2004)