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.