Thickness dependence of the effective dielectric constant in a thin film capacitor

The static value of the effective dielectric constant in a thin film capacitor is simulated by means of the local field theory. The value of it shows a sharp decrease as the film thickness is decreased in an ultrathin film geometry. This phenomenon is due to the size effect intrinsic to a thin film structure and has nothing to do with the material aspect. The decrease is more remarkable for larger values of the bulk dielectric constant. It is recovered by inserting interface layers with larger atomic polarizability between the film and the capacitor electrode.