Contacting Systems
Alan Owens · 2019
Contacting systems can be broadly classified into two groups. These are Ohmic and Schottky contacts. Low-resistance or “ohmic” contacts have linear current-voltage characteristics, that is, there is an unimpeded transfer of either carrier from one material to another, which does not depend on the polarity or direction of the bias. Contacting can be achieved by several methods, such as applying metal-bearing paints and pastes, such as Aquadag, melting metals directly on the semiconductor surface, evaporation, sputtering, molecular beam epitaxy, ion-implantation and others. All semiconductor devices generally need at least one ohmic contact; it is often the quality of this contact that significantly affects the performance of semiconductor devices. In contrast to ohmic-like contacts, Schottky, or blocking, contacts have current-voltage characteristics that are non-linear and asymmetric as shown by the solid line. The conduction properties of the contact are determined by the current transport mechanisms discussed in the Schottky barrier section.