Electronic properties of quantum-dot molecules

We investigate the electronic structure of several double quantum dot systems: (i) hetero-dot artificial molecules built from two CdS chemically synthesized nanocrystals and (ii) two vertically stacked pyramidal self-organized InAs/GaAs quantum dots. The calculations are performed using the empirical tight-binding approach. The results of calculations show significant coupling between the nanocrystals that form a quantum-dot molecule. When two quantum dots are close enough, the strong coupling can split and reorder energy levels, change state symmetries and make substantial changes in optical spectra. Formation of double-dot states having bonding and antibonding character by analogy to diatomic molecules is shown.