Fermi-level pinning and interface states atCaF2/Si(111)

Abstract

We examined the electronic structure at ${\mathrm{CaF}}_2$/Si(111) interfaces using the linear muffin-tin orbitals method in the atomic-sphere approximation based on the local-density formalism. The Fermi level is pinned by interface states for the model with eightfold-coordinated Ca atoms at the interface, but Fermi-level pinning does not occur in models in which F atoms are dissociated from interface ${\mathrm{CaF}}_2$. The interface states we obtained agreed well with experiments. We will discuss the interface atomic structure by comparing the electronic structures with experiment.