Effect of a glassy membrane on the Schottky barrier between silicon and metallic silicides

Abstract

We present a model for Schottky barriers on silicon based upon the formation of a glassy membrane layer between the last metal layer and silicon. We postulate that this membrane has the properties of a semiconducting glass with quasiparticle states in the gap, characterized by a negative correlation energy. These states effectively pin the Fermi level with respect to the silicon bands at a level depending on the silicon-metal molecular bonding in the membrane layer. This model thus gives a physical picture for Fermi-level pinning which agrees semiquantitatively with Schottky barrier measurements.