Resonance electronic excitation energy transfer in the quantum dot system.

Microscopic theory of the nonradiative energy transfer in a system of III-V semiconductor quantum dots is elaborated in our work. The energy transfer both due to direct Coulomb and due to exchange interactions between two quantum dots (energy donor and acceptor) is considered. An analysis of energy transfer process is performed in the frame of the Kane model that provides the most adequate description of the real energy spectra and wave functions of III-V semiconductors. The density-matrix method is applied, which enabled us to analyze the energy transfer rate both in the weak-interaction approximation and in the strong-interaction approximation. For the first time the detailed analytical calculations of the exchange energy transfer rate for the quantum dot system are performed. The analytical expressions for contributions to the transfer rate are derived. The numerical calculations showed that at nearly contact distances between two quantum dots the rate of the energy transfer due to the direct Coulomb interaction as well as by exchange interaction can reach the saturation. At the small distances, these two contributions can be of the same order and can have the same value in the saturation range. It is revealed that the exchange interaction should be taken into consideration in qualitative describing the energy transfer at small distances between the quantum dot donor and the quantum dot acceptor.