We show that a diatomic dot molecule made of two identical, vertically stacked, strained InAs/GaAs self-assembled dots exhibits an asymmetry in its single-particle and may-particle wavefunctions. The single-particle wave function is asymmetric due to the inhomogeneous strain, while the asymmetry of the many-particle wavefunctions is caused by the correlation induced localization: the lowest singlet 1Σg and triplet 3Σ states show that the two electrons are each localized on different dots within the molecule, for the next singlet states 1Σu both electrons are localized on the same (bottom) dot for interdot separation d> 8 nm. The singlet-triplet splitting is found to be ∼0.1 meV at inter-dot separation d=9 nm and as large as 100 meV for d=4 nm, orders of magnitude larger than the few meV found in the large (50 - 100 nm) electrostatically confined dots.
@article{arxiv.cond-mat/0412172,
title = {Asymmetry in self-assembled quantum dot-molecules made of identical InAs/GaAs quantum dots},
author = {Lixin He and Gabriel Bester and Alex Zunger},
journal= {arXiv preprint arXiv:cond-mat/0412172},
year = {2009}
}