NSTI Nanotech 2009

The INGAAS/GAAS Quantum Dots Under Effective and Ab Initio Treatments: Comparison and Results

I. Filikhin, V.M. Suslov, B. Vlahovic
North Carolina Central University, US

Keywords: quantum dots, single carrier levels, Coulomb interaction, excitons, optical properties


An effective approach for describing the electronic structure of InGaAs/GaAs quantum dots (QDs) is presented. We model QDs based on a single sub-band approach with an energy dependent electron effective mass. The model assumes that the total effect of inter-band interactions, strain and piezoelectricity can be taken into account by an effective potential. Using this approximation, we define a strength parameter of the effective potential to reproduce capacitance-gate-voltage (CV) experimental data for InAs/GaAs QDs. In the present work, we expand the model to describe InxGa1-xAs QDs with significant Ga fractions. It is found that our model accurately describes CV and photoluminescence (PL) data for QDs with assumed 22% Ga fraction. The model also reproduces the experimental data for Coulomb shifts of exciton complexes (X+, X-, XX). We compared our results with atomistic pseudopetential and ab initio calculations obtained with an 8-band kp-Hamiltonian approach. The strength of the electron and heavy hole confinement is found to be weaker in the ab initio model than in the atomistic pseudopotential approach.
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