Atomistic Pseudopotential Theory of Droplet Epitaxial GaAs/AlGaAs Quantum Dots

Abstract

In this chapter, following the introduction to the basic electronic properties of semiconductor quantum dots (QDs), we first briefly introduce our atomistic methodology for multi-million atom nanostructures, which is based on the empirical pseudopotential method for the solution of the single-particle problem combined with the configuration interaction (CI) scheme for the many-body problem which were developed in the solid-state theory group at the National Renewable Energy Laboratory over the past two decades. This methodology, described in Sect. 14.2, can be used to provide quantitative predictions of the electronic and optical properties of colloidal nanostructures containing thousands of atoms as well as epitaxial nanostructures containing several millions of atoms. In Sect. 14.3, we show how the multi-exciton spectra of a droplet epitaxy QD encodes nontrivial structural information that can be uncovered by atomistic many-body pseudopotential calculations. In Sect. 14.4, we investigate the vertical electric field tuning of the fine-structure splitting (FSS) in several InGaAs and GaAs QDs using our atomistic methodology. We reveal the influence of the atomic-scale structure on the exciton FSS in QDs. Finally, a comprehensive and quantitative analysis of the different mechanisms leading to HH–LH mixing in QDs is presented in Sect. 14.5. The novel quantum transmissibility of HH–LH mixing mediated by intermediate states is discovered. The design rules for optimization of the HH–LH mixing in QDs are given in this section.