**7. Conclusion**

This chapter considers the temperature behavior of luminescent semiconductor quantum dots that have formed by thermal and ion beam methods. Analytical expressions characterizing the PL intensity of confined excitons were obtained on the basis of a generalized energy scheme for direct or indirect excitation of QDs.

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Five types of temperature dependences of the luminescence of quantum dots were considered, and model parameters that affect the shape of the temperature curves were analyzed. The main variables of these models are the ratios of the rates of competing relaxation processes as well as the differences of their activation barriers. The derived expressions allow us to analyze and explain the experimentally observed luminescence temperature dependences of the most diverse form.

The models presented in this chapter were tested on the example of temperature dependences of PL silicon nanoclusters in silica matrix under different optical excitations. High informativeness and sensitivity of analytical expressions to dimensional effects and structural disordering in QDs substance are shown.

It was found that indirect excitation of Si QDs leads to a decreasing PL temperature dependence, which is due to a three-stage relaxation process. At the same time, the temperature dependences of PL upon direct excitation of silicon quantum dots are in the form of curves with a maximum and are characterized by a two-stage relaxation process. The increased effect of Si QD photoluminescence with increasing temperature, which is observed experimentally, can be explained by an increase in the density of triplet excitations acting as radiative states.

The observed structural and dimensional effects are explained using a hypothetical configurational scheme. We have found that the confined exciton effect in silicon nanoclusters manifests itself in the form of a decrease in the thermal activation barriers of nonradiative processes. Crystallization of the silicon amorphous nanoclusters also leads to a sharp decrease in the energy parameters of all thermally activated processes.

The data presented in this chapter can be used in the field of new functional materials and devices for nanophotonics. The developed ideas here can be considered as a tool for predicting and controlling the luminescent properties of quantum dots under their composition, size, and structural ordering change.
