Some Properties of Dirty Contacts on Semiconductors and Resistivity Measurements by a Two-Terminal Method

Abstract

The surface and bulk properties of semiconductors have been studied by a two‐terminal method using dirty contacts. These contacts are defined as ones that are easily applied and removed and that are separated from the bulk by surface states, oxides, adhered gasses, and chemical films. The method essentially involves measuring the resistance‐voltage (R‐V) characteristics from the millivolt range up to about 100 V, and from these data the sample resistivity can be obtained directly. The effect of work damaging or etching the semiconductor surface can be readily evaluated. By observation of the shape of the R‐V curves it is possible to separate the bulk from the surface effects, calculate the surface barrier height and thickness from tunneling equations, and determine whether the barrier is a surface film or due to metal‐semiconductor contact potential difference. An application of the theory of electric field tunneling of Holm to the data of silicon carbide gives values of about 2.4 eV for the barrier height and 13 Å for the barrier width of the film on the surface. Sufficient information is included on electrode techniques and pitfalls so that the experimentalist can readily make the measurements. Efforts were concentrated on silicon carbide and silicon, but the techniques are applicable to all types of semiconductors.