Exploring excitonic properties of vertically coupled semiconductor nanostructures using Path Integral Quantum Monte Carlo

Abstract

In this thesis electron and exciton systems in atomistic model semiconductor nanostructures are theoretically studied using the Path Integral Quantum Monte Carlo (PI-QMC) technique. The application of this method gave us the opportunity to fully investigate Coulomb interacting systems at finite temperature, with an exact treatment of the impact of inter-particle correlations on the properties of a system without relying on complex trial functions or basis sets. Using confining potentials calculated from a strained atomistic model of semiconductor vertically stacked dot and ring nano-structures gave us insight into the ground state properties of vertically stacked quantum dot and ring systems, including the interplay between vertical electric and piezoelectric fields. Interactions between external electric fields, strain and piezoelectric potential revealed novel and unique for the stacked structures properties. The recombination rate of exciton (X) and bi-excitons (XX) as a function of structure vertical separation is investigated and compared against recombination in a multiple quantum dot, both with and without the application of an external electric field. The novel piezoelectric properties of stacked dots and rings in the presence of a vertical electric field, inducing in-plane charge probability distribution switching of an exciton, are explored. Results obtained from calculations of the lateral polarisability of X and XX indicates the possibility of experimental verification of this unique phenomenon.