Dielectric properties of interfaces*

The description of dielectric properties of interfaces is a key ingredient for models of heterogeneous materials. We investigated several interfaces, including Si/Si₃N₄, Si/H₂O, Si/vacuum, using first principle electronic structure methods. We present a definition of the dielectric response of a semiconducting interface obtained by using a spectral decomposition of the dielectric matrix, and by localizing its eigenvectors in appropriately chosen regions of space. The interfacial dielectric response is then used to define an electronic thickness of the interface and spatial dependent band offsets.