Katherine Gallegos Rosas

Hall effect measurement enables the determination of key semiconductor parameters such as carrier mobility, carrier concentration, and Hall coefficient. In this measurement, a current is applied through the sample in combination with a perpendicular magnetic field. The resulting potential (Hall voltage) is measured, and by knowing the sample thickness and resistivity, typically measured by the van der Pauw method, the charge-carrier concentration and carrier mobility can be calculated. Measurements are typically performed from room temperature to 200 °C in air, but temperatures from -150 °C to 600 °C are available upon request. Typical measurement ranges: Charge carrier concentration: ~107–1021cm-3, Resistivity: ~10-4–107Ωcm, Mobility: ~0.1–107 cm2/Vs.

Four-point probe measurement is a method used to measure the resistivity and conductivity of conductive and semiconductive materials, including thin films. As the method uses separate current and voltage probes, the impact of contact resistance is minimized compared to a traditional two-point probe measurement. In a standard four-probe measurement setup, the probes are equally spaced from one another. By applying a known current through the two outer probes and measuring the voltages at the inner probes, sheet resistance can be determined by using Ohm's law. When samples have an arbitrary shape, it is common to use the van der Pauw method. In this case, the four probes are placed around the perimeter of the sample. Measurements can be performed from room temperature to 200 °C in air.