Nano-Scale Profile of the Dielectric Constant Near the Si/oxide Interface: A First-Principles Approach

Abstract

Spatial variation in dielectric constants near the Si/SiO2 interfaces has been revealed using the first-principles ground-states calculations in external electrostatic fields. It has been shown that both the optical and the static dielectric constants change abruptly in the vicinity of the SiO2/Si interfaces, while the energy gap changes gradually on SiO2 side. These results indicate that the profile of dielectric constant is determined by the local polarization which directly reflects the local atomic arrangement. Dielectric properties of isolated ultra-thin Si(111), SiO2, and La2O3(0001) films have also been investigated. Both the optical and the static dielectric constants of oxide films hardly depend on the film thickness and the spatial variation of the local dielectric constant is also very small as contrasted to the semiconducting Si film.