Field emission from a metal covered with a semiconducting layer: A model calculation

Abstract

The electron field emission from a metal covered with a thin layer of a semiconductor with electron affinity χ and dielectric constant ɛ is considered. The model takes into account the metal-semiconductor (Schottky) barrier of height ϕ_b, the conduction current inside the semiconductor, and the band bending at the semiconductor-vacuum interface due to the external field penetration. For thick films under moderately high electric fields, the metal-semiconductor interface does not influence the emission behaviour whereas for thin films, the interface plays an important role, depending on the barrier heights. In particular, for χ/ϕ_b<ε^2/3 the I–V characteristics will, for strong fields, be dominated by the field emission process at the interface. In such cases important deviations from Fowler-Nordheim behaviour are found.