Four-probe method:

Van der Pauw method:

This method involves applying a current and measuring voltage using four small contact on the circumference of a flat, arbitrarily shaped sample of uniform thickness.

The resistivity can be obtained from a total of eight measurements that are made around the periphery of the sample with the configurations as shown in Figure 25.04.

Figure 25.04: Schematic of different configurations involved in van der Pauw method.

Once all the voltages are taken, two values of resistivity ρ_A and ρ_B can be derived as follows: