Relation between current-voltage characteristics and interface states at metal-semiconductor interfaces

In the case of metal-covalent semiconductor interfaces, the ‘‘pinning’’ of the metal Fermi level was attributed to large densities of interface states by Bardeen, 35 years ago. These interface states are usually thought to be in equilibrium with the metal. But capacitance measurements show unambiguously the existence of states in equilibrium with the semiconductor, even for cleaved contacts. Freeouf argued recently that this kind of states would influence I-V characteristics. Here, some examples of such a correlation between interface states spectra and I-V nonidealities are presented for Au-InP and Au-Si contacts.