Binding energy of a quasi-molecule in nanoheterostructures

Abstract

This paper shows that the appearance of a quasi-molecule consisting of two cadmium sulfide quantum dots located in a borosilicate glass matrix with electrons localized above the surfaces of the quantum dots has a threshold character and can occur in a nanosystem in which the distance D between the surfaces of the quantum dots is determined by the condition Dc(1)≤D≤Dc(2) (where Dc(1) and Dc(2) are certain critical distances). A substantial increase (by more than an order of magnitude) is detected in the binding energy of the singlet ground state of a quasi-molecule by comparison with the binding energy of a biexciton in single-crystal cadmium sulfide. It is established that the main contribution to the binding energy of the quasi-molecule is from the electron–hole exchange-interaction energy, which is substantially greater than the contribution of the electron–hole Coulomb-interaction energy.