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