Intrinsic surface states and Fermi-level pinning at metal–semiconductor interfaces

Abstract

We find that the well-known transition in the Fermi-level pinning behavior of metal–semiconductor contacts can be quantitatively characterized in a fundamental way. Our model makes use of the clean semiconductor surface state energies, predicts the onset of the covalent–ionic transition, and explains strong Fermi-level pinning at metal contacts to covalent materials with large optical gaps and low bond polarizabilities.