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Asymmetry in self-assembled quantum dot-molecules made of identical InAs/GaAs quantum dots

Lixin He·Gabriel Bester·Alex Zunger
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Abstract

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 $^1Σ_g$ and triplet $^3Σ$ states show that the two electrons are each localized on different dots within the molecule, for the next singlet states $^1Σ_u$ both electrons are localized on the same (bottom) dot for interdot separation $d>$ 8 nm. The singlet-triplet splitting is found to be $\sim 0.1$ 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.

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Lixin He, Gabriel Bester, Alex Zunger. 2005-03-28. Asymmetry in self-assembled quantum dot-molecules made of identical InAs/GaAs quantum dots. https://doi.org/10.1103/physrevb.72.081311

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