Determination of contact resistance in metal-semiconductor structure

As is well known, the metal-semiconductor contact is clearly a component of any semiconductor device. At the same time, such contacts cannot be assumed to be as low resistance as that two connected metals. In particular, a large mismatch between the Fermi energy of the metal and semiconductor can result is a high-resistance rectifying contact. The proper choice of materials can provide a low resistance ohmic contact. However, for a lot of semiconductors there is no appropriate metal available. Instead one then creates a tunnel contact. Such contact consists of a thin barrier - obtained by heavily-doping the semiconductor - through which carriers can readily tunnel. Contact formation is also affected by thin interfacial layers and is typically finished off with a final anneal or alloy formation after the initial deposition of the metal. In this paper, our work aims to describe each of these contacts; we end this study by determining the contact resistance between a metal and a thin semiconductor layer.