A two steps CVD process for the growth of silicon nano-crystals

We have developed a two steps chemical vapor deposition (CVD) process which permits to dissociate the nucleation and the growth of silicon nano-crystals. In the first step, silicon “clusters” of a diameter below 1 nm are nucleated by exposure of the SiO2 substrate to SiH4. In the second step, these clusters are grown selectively using SiH2Cl2 as silicon precursor. TEM analysis shows that the silicon quantum dots (Si-QDs) obtained with this process are mono-crystalline. The main advantage of this two steps process is that the size dispersion is sharpened compared to a standard one step process because of the dissociation of the nucleation and the growth of the Si-QDs.