Tight-Binding Theory of Quantum-Dot Quantum Wells: Single-Particle Effects and Near-Band-Edge Structure

Published

May 1, 2003

Author(s)

Garnett W. Bryant, W Jaskolski

Abstract

Electron and hole states of multishell CdS/HgS/CdS quantum-dot quantum-well nanocrystals are determined by use of atomistic tight-binding theory. Single-particle energies, symmetries and charge densities, trapping in the internal quantum well, transition energies, and optical spectra are determined. Comparison with experiment shows that tight-binding theory provides a good description of nanosystems with monolayer variations in composition. Tight-binding theory correctly predicts the Stokes shift between the dim ground state and the lowest optically active transition. The energy splitting between the lowest two optically active transitions is also correctly described. Comparison with previous multiband effective mass theory shows that both theories provide a similar picture for the single-particle states but that the tight-binding theory provides a much better description of observed transition energies. Calculations are done for different nanocrystal shapes, different positions and size of the internal quantum well, different values for the spin-orbit coupling and the band offset. Results are robust to these variations indicating that the physical character of states in quantum-dot quantum wells is determined by the effects of global confinement in the dot and local confinement in the internal well rather than by the specific details of the quantum-dot quantum-well size, shape or geometry.

Citation

Physical Review B (Condensed Matter and Materials Physics)

Volume

67

Issue

No. 20

Pub Type

Journals

Keywords

electronic structure, excitons, nanocrystals, optical spectra, quantum dots, tight-binding

Citation

Bryant, G. and Jaskolski, W. (2003), Tight-Binding Theory of Quantum-Dot Quantum Wells: Single-Particle Effects and Near-Band-Edge Structure, Physical Review B (Condensed Matter and Materials Physics) (Accessed April 19, 2024)