Atomistic Simulations of Electronic and Optical Properties of Semiconductor Nanostructures

Abstract

We present a tutorial introduction to atomistic calculations of electronic and optical properties of semiconductor nanostructures. The systems of interest, self-assembled quantum dots and colloidal nanocrystals, are composed of thousands to millions of atoms, beyond the applicability of ab initio schemes. Our approach, implemented as the QNANO computational package, consists of (1) atomistic geometry optimization using the valence force-field (VFF) model, (2) calculation of single-particle states confined in a nanostructure using the tight-binding scheme, (3) computation of Coulomb interaction matrix elements using the atomistic wave functions, and (4) calculation of multi-exciton spectra and optical response functions using the configuration interaction approach coupled with Fermi’s Golden Rule. We illustrate this methodology by computing the single-particle states and the exciton fine structure of a self-assembled quantum dot, and by analyzing the multiexciton generation processes in colloidal nanocrystals.