2007 NSTI Nanotechnology Conference and Trade Show - Nanotech 2007 - 10th Annual

Pseudopotential theory of electronic excitations in semiconductor nanostructures

A. Franceschetti and M.C. Troparevsky
National Renewable Energy Laboratory, US

quantum dots, excitons, pseudopotentials

The calculation of the optical and electronic properties of semiconductor nanopstructures is still based for the most part on highly approximated, continuum-like models such as the effective-mass approximation. These models do not take into account the atomistic structure of the quantum dots, thus missing crucial features that become essential when the system is only a few nanometers in size. We have recently developed an atomistic pseudopotential approach to the calculation of excited states in semiconductor nanostructures. This approach involves two steps: (i) The electronic potential is expanded as a superposition of screened atomic pseudopotentials, which are fitted to experimental bulk transition energies, effective masses, and deformation potentials, and to first-principles bulk electronic wave functions. The single-particle Schroedinger equation for the nanostructure is then solved using powerful, O(N) methods. (ii) The electronic excited states (such as excitons, multi-excitons, etc.) are then calculated by solving the many-particle Scroedinger equation in a basis set of Slater determinants, obtained by promoting one or more electrons from the valence band to the conduction band. I will discuss applications of the pseudopotential method to predict the optical absorption and emission spectra of charged excitons, bi-excitons and tri-excitons in CdSe colloidal quantum dots.

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Nanotech 2007 Conference Program Abstract


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