Synthesis of mono and bi-layer of Si nanocrystals embedded in a dielectric matrix by e-beam evaporation of SiO/SiO2 thin films

Si nanocrystals (ncs) were synthesized by e-beam evaporation of SiO/SiO2 multilayer structures and subsequent annealing at high temperatures. We focused our attention on the possibility to manipulate the ncs dimension by changing the SiO layer thickness. Time of flight secondary ion mass spectrometry and X-ray photoelectron spectroscopy analyses of the annealed samples indicated that the thermal treatment induces a phase separation in the SiO layer. The formation of Si nanocrystals was confirmed by high-resolution transmission electron microscopy, although in the thinnest layers (below 2 nm) the Si clusters are probably amorphous. Preliminary results indicate that a similar approach is suitable also for synthesizing Ge nanocrystals.