CALCULATED ELECTRONIC-STRUCTURE AT THE CAF2/SI(111) INTERFACE

The electronic structure of the CaF2/Si(111) interface is studied using the linear muffin-tin orbitals in the atomic sphere approximation within the local density approximation. This involves three structural models of the interface: For the model with sevenfold coordinated Ca atoms at the interface, the Fermi level is pinned by interface states originating in a dangling bond from the interfacial Si atom. For models with a CaF layer at the interface, interface states in the Si band gap separate into occupied and unoccupied states. The energy dispersion calculated for the occupied interface states of the model with the interfacial Ca atom at the T4 site agrees better with angle-resolved photoelectron spectroscopy data than that of the model with the Ca atom at the H-3 site.