Spatially indirect excitons and exciton quasimolecules in nanosystems with double quantum dots

In mini-review, deals with the theory of exciton quasimolecules in a nanosystem consisting of double quantum dots of germanium synthesized in a silicon matrix. An exciton quasimolecule was formed as a result of the interaction of two spatially indirect excitons. It is shown that, depending on the distance D between the surfaces of the quantum dots, spatially indirect excitons and of exciton quasimolecules was formed in the nanosystem. The binding energy of the singlet ground state of the exciton quasimolecule has been gigantic exceeding the binding energy of the biexciton in a silicon single crystal by almost two orders of magnitude. The emergence of a band of localized electron states in the band gap of the silicon matrix was found. This band of localized electron states appeared as a result of the splitting of electron levels in the chain of germanium quantum dots.