Current transport in metal semiconductor contacts—a unified approach

Abstract

A unified approach to current transport at metal-semiconductor junctions is employed which includes thermionic emission, thermionic-field emission, and field emission. Rather than the many expressions for the current density which are available in the literature with their various ranges of validity, a single expression of general validity is presented which allows the I–V characteristics of a junction to be computed from a relatively simple double integration. The approach is valid for arbitrary doping and barrier shape for a wide range of temperatures for the general case of a many valley semiconductor. It may be easily extended to p-type materials. The generalized WKB-type of approximation used in the analysis allows the current density to be expressed in terms of the product of a transmission probability and a supply function. The supply function is such that, for a given valley, there is a Richardson constant applicable to all transport processes.