Measurement of Sheet Resistivities with the Four-Point Probe

The "four-point probe" has proven to be a convenient tool for the measurement of resistivities. For a description of the method see a paper by L. Valdes,1 which gives the functional relationship between the resistivity, p, and the voltage and current readings for various geometries. Later, A. Uhlir evaluated functions2 which give the relationship for additional geometries. All these treatments are concerned with threedimensional structures infinite in at least one direction. For diffused layers, a similar relationship is needed for the evaluation of sheet resistivities on various sample shapes. This is a two-dimensional problem which is treated here for various finite sample sizes. With the solution, however, it also is possible to obtain body resistivities 011 thin slices of the same finite geometries.