The approach of superlattices to enable the size control of different nanocrystalline materials was investigated. In case of size controlled Si nanocrystals synthesized by SiO/SiO₂ superlattices this approach enables a precise bandgap engineering of well passivated nanocrystals. Which results in a tunable luminescence signal, a resonant energy transfer to Er ³⁺ ions and the confirmation of the quantum confined origin of the luminescene and the prove of optical amplification. In case of Zr based dielectrics the size control by the superlattice approach enables the stabilization of the tetragonal phase, which is favorable for high capacitance applications. For HfO₂ an additional doping of the films, e.g. by Si atoms for the phase stabilization is necessary. Doping or interlayer additionally improves the electrical performance of the dielectrics.