[en] The high-dose ion ion implantation followed by a thermal-annealing step represents a flexible most promising procedure for the synthesis of buried nanocrystals in a solid. The processes of the structure formation in the solid matrix are however much more complicated compared with chemical-reaction slopes in solution. The first aim of this thesis consisted in the finding of the explanation for the unusual structure formation in the case of CdSe in SiO₂. Thereby a computer simulation was established, which allowed to meet qualitative conclusion regarding a relatively low number of simulation parameters. Thereby it dealt with a particle-Monte-Carlo simulation. Under inclusion of usually neglected factors, here the alteration of the matrix during the implantation and the role of defects in the segregation formation in amorphous SiO₂, for the first time a consistent explanation both for the generation of nanocrystal bands in the depth and for the structures in the implanted region could be given. Furthermore it was studied how far the buried CdSe nanocrystals can be doped with sulfur. As it could be shown the ion-beam synthesis represents a suitable procedure in order to synthetisize buried CdS_xSe_1-x mixed crystals on the base of purely solid-state processes in SiO₂. The third aim of this thesis consisted in the discussion of an alternative non-thermal tempering behaviour on the base of pulsed laser radiation