Tight-binding calculations of SiGe alloy nanocrystals in SiO2 matrix.

In the empirical tight-binding approach we study the electronic states in spherical SiGe nanocrystals embedded in SiO2 matrix. For the SiGe alloy and the matrix we use the virtual crystal approximation. The energy and valley structure of electron states is obtained as a function of Ge composition and nanocrystal size. Calculations show that the mixing of hot electrons in the nanocrystal with the electrons in wide band gap matrix is possible and this mixing strongly depends on the Ge composition in the nanocrystal.