Ionicity and the theory of Schottky barriers

Abstract

We have investigated the role of ionicity in metal-semiconductor Schottky barriers by examining interfaces of increasing semiconductor ionicity. The electronic structure of four separate interfaces consisting of jellium (of A1 density) in contact with the (111) surface of Si and the (110) surfaces of GaAs, ZnSe, and ZnS is investigated through the use of a self-consistent pseudopotential method. The barrier height and the surface density of states in the semiconductor band gap are determined. The phenomenological index of interface behavior $S$ (studied by Kurtin, McGill, and Mead for semiconductors of different ionicity) is discussed in terms of a simple model involving metal-induced states in the semiconductor gap.