First principle investigations of the dielectric properties of Si3N4 thin films*

We have investigated the dielectric properties of silicon nitride thin films with thickness below 10 nm, by using first-principles density functional theory calculations. We find a substantial decrease of the static dielectric constant as the size is reduced, and the variation of the response in proximity of the film surfaces play a key role in the observed decrease. In addition, amorphization of the films can bring further reduction of both the static and optical dielectric constants.