Atomic structure of the amorphous nonstoichiometric silicon oxides and nitrides

In addition to amorphous $\mathrm{SiO_2}$ and $\mathrm{Si_3N_4}$, the two key dielectric film materials used in modern silicon devices, the fabrication technology of nonstoichiometric $\mathrm{SiO}_x\mathrm{N}_y$, $\mathrm{SiN}_x$, and $\mathrm{SiO}_x$ compounds is currently under development. Varying the chemical composition of these compounds allows a wide range of control over their physical — specifically, optical and electrical — properties. The development of technology for synthesizing such films requires a detailed understanding of their atomic structure. Current views on the atomic structure of nonstoichiometric silicon nitrides and oxides are reviewed and summarized.