Laser-Driven Hole Trapping in a Ge/Si Core–Shell Nanocrystal: An Atomistic Configuration Interaction Perspective

• Published in: Journal of physical chemistry. C Vol. 119; no. 45; pp. 25606 - 25614
• Main Authors: Hermann, G, Tremblay, J. C
• Format: Journal Article
• Language: English
• Published: American Chemical Society 12.11.2015
• ISSN: 1932-7447; 1932-7455
• DOI: 10.1021/acs.jpcc.5b08606

This contribution reports on the first example of laser-driven charge carrier confinement in a solid state quantum dot investigated using a fully atomistic, correlated many-electron ansatz. Specifically, a Ge/Si model nanocrystal is designed to retain the main structural characteristics and excitonic properties of experimentally observed self-assembled pyramidal heterostructures. State-selective laser excitations yielding hole confinement in the Ge nanostructure are simulated using the reduced density matrix variant of the time-dependent configuration interaction method (ρ-TDCI). The degree of carrier localization in the quantum dot is determined by analyzing the correlated one-electron densities from configuration interaction electronic states at a singles level. Additionally, dissipation and pure dephasing are included to treat the coupling of the local core–shell structure with the vibrations of the surrounding silicon matrix. For this purpose, a new microscopic model for these nonadiabatic coupling rates is derived. The results reveal that, despite the presence of dissipation, charge carriers can be efficiently confined by localized optical excitations in the model Ge/Si quantum dot to create long-lived, large permanent dipoles in the nanocrystal.