Path integral quantum Monte Carlo simulations of coulomb correlations in semiconductor nanostructures
Abstract
In this work the Path Integral quantum Monte Carlo (PI-QMC) method has been
used to study exciton complexes in semiconductor nanostructures. This powerful
technique allows for coulomb correlations in these complexes to be correctly
treated, and at the same time allowing for nite temperature simulations in an arbitrary
external potential without the need for complicated trial function or basis
set information.
Quantum dots and rings were modelled using both analytic potentials, and by
potentials derived from atomistic models of these structures, including strain and
piezoelectric e ects. The e ect of strain and the piezoelectric potential on quantum
rings is explored, and rings are shown to have a unique strain and piezoelectric
pro le which directly impacts observables.
This unique piezoelectric potential in quantum rings is exploited by use of vertical
electric elds, to induce a novel lateral switching of the exciton and biexciton
probability distributions when the direction of the applied eld is switched.
Calculations of in-plane polarizability suggest the switching would be observable
experimentally.
The diamagnetic susceptibility of quantum rings and dots are investigated, and
accurate reproduction of experimental results are shown { which require the proper
treatment of coulomb correlations.
Finally, the transition between a bound and anti-bound biexciton in a core/shell
Type-II colloidal quantum dot, with increasing shell thickness is for the rst time
theoretically shown. Excellent agreement with experimental results are seen, and
these results are contrasted with previous perturbative results which miss this transition
from the literature.