Stoichiometry of silicon-rich dielectrics for silicon nanocluster formation

Silicon photonics has been bred by several techniques including Chemical Vapour Deposition (CVD) and ion implantation amongst others in order to synthesize silicon nanoclusters with CMOS-compatible technologies. Most of these techniques end up relying on the formation of nanoclusters through the diffusion and segregation of silicon atoms in a silicon-rich dielectric matrix. In this work we present a parallel analysis on silicon rich dielectric layers obtained by different methods. X-Ray Photoelectron Spectroscopy, ellipsometry and photoluminescence are used to characterize Low Pressure CVD and Plasma Enhanced CVD samples in the same theoretical silicon excess range. The analysis shows that independently on the obtaining method the initial concentration of silicon excess can be used to estimate some properties. The actual binding of the atoms can change as well regardless of their initial quantity. However secondary parameters such as the obtaining temperature and the nitrogen concentration in the layer have to be taken into account. Therefore, experimental parameters such as the flow ratio between reactant gases or the refractive index prove to be insufficient if samples obtained by different methods are compared.