Introduction

Rapid advances in chemical synthesis and fabrication techniques have led to novel nano-sized materials that exhibit unique and often unforeseen properties. The design of nanoelectronic devices requires a clear understanding of the fundamental properties of nanomaterials. Semiconductor quantum dots (QDs) and single-walled carbon nanotubes (SWCNTs) are two of the most promising examples of low-dimensional nanomaterials. Both QDs and SWCNTs can be considered nanoscale derivatives of bulk materials. The 0-D confinement of charge carriers in QDs results in the quantization of their electronic energy levels and is responsible for new physical phenomena. In addition to carrier-phonon interactions, charge confinement in both nanostructures leads to strong Coulomb interaction between electrons and holes, and, therefore, to excitonic effects. The character of excitons and their computational treatment are different in the two systems. For example, in strongly confined QDs, both the Coulombic and the kinetic energies of electrons and holes rise with decreasing QD radius.