Atomistic tight-binding computations in electronic structures and optical properties of type-II CdTe/CdSe core/shell nanocrystals

摘要

I perform a detailed theoretical study of the characteristic electronic structures and optical properties of type-II CdTe/CdSe core/shell nanocrystals of the experimentally relevant dimensions by means of atomistic sp(3)s* empirical tight-binding theory (TB) and configuration interaction description (CI) with the aim to evidently understand the significance of the CdSe growth shell. Based on the theoretical results, the single-particle spectra, density of states (DOS), charge densities, overlaps of electron and hole wave function, oscillation strengths and excitonic energies are mainly analyzed as a function of CdSe shell thicknesses. The detailed analysis elucidates and quantifies the sensitivity of shell thickness in determining the electronic structures and optical properties of CdTe/CdSe core/shell nanocrystals. In addition, I emphasize that the atomistic tight-binding calculations show a reasonable congruence with the experimental results. As can be seen from the atomistic computations, I summarize that the efficient manipulation of structural and optical properties of CdTe/CdSe core/shell nanocrystals is theoretically achieved by introducing and changing the CdSe growth shell thickness. Finally, the comprehensive knowledge successfully exposes the important physical factors that influence the atomistic behaviours of type-II CdTe/CdSe core/shell nanocrystals for a given growth shell thickness which can aid in the understanding of the physical properties of a wider class of type-II nanoscale heterostructures, thus leading to a guideline for the design of their electronic and optical properties before implementing to the novel electronic nanodevices. (C) 2015 Elsevier B.V. All rights reserved.