Study of the Electronic Properties of Quantum Dots.

Abstract

Quantum dots (QDs) have captured the substantial attention of nanotechnology due to their unique optical and magnetic properties. The new element here is the physical con nement which creates localized electronic states and tunable energy gap in these systems. Through this thesis electronic properties of di erent types of quantum dots are discussed. In chapter 1, we introduce a literature survey about these QDs. In chapter 2, we study the electronic properties of semiconductor GaAs quantum dot (QD) under the e ect of constant magnetic eld with two types of quantum con nement potentials: parabolic and inverse parabolic con nement potential. As a function of magnetic eld we observed Anti crossing between the ground state energy and the rst excited state energy. Within the tight binding model, electronic energy levels of graphene quantum dots of circular, hexagonal, and triangular shapes are studied. In general two types of edge states, located nearby the Dirac point can be discerned, the zero energy states (ZES) that are degenerate and located exactly at = 0 and the dispersed edge states (DES) that ll the low-energy domain within the gap and are symmetrically distributed with respect to = 0. As a comparison between the two types of the QDs we calculated the transition energy inside each QD, we obtained this energy in the infrared light range.