Density Functional Theory Modeling of (001)Si--Oxynitride Interfaces.

Four interface models for crystalline oxynitride on (001)Si substrates are proposed and investigated. All four models are proposed to model thin oxynitride films on Si substrates, according to experimental findings and theoretical studies on amorphous oxynitride films and nitrogenated SiO₂. State-free insulating interfaces were obtained by expanding the bulk oxynitride cell by approximately 12% and 1% along the [100] and [010] axes, respectively, and interfacing it with (001)Si. Results demonstrate state-free insulating interfaces for all models with, however, valence-band offsets slightly above or below 1 eV. The significant decrease in the valence-band offsets is mainly attributed to the significant expansion of the oxynitride's lattice constant to lattice-matched (001)Si, as well as to the high concentration of nitrogen atoms in the oxynitride bulk. [ABSTRACT FROM AUTHOR]