Fyrpunktsmätningar

Fyrpunktsmätningar, also known as four-point probe measurements, is a common experimental technique used to determine the electrical resistivity of a material. The method involves using four equally spaced collinear probes to pass a current through the outer two probes and measure the voltage drop across the inner two probes. This configuration helps to minimize contact resistance effects, which can be a significant source of error in other resistivity measurement methods.

The core principle behind fyrpunktsmätningar is that by measuring both the current and the voltage, the resistance can be calculated using Ohm's Law. However, the specific geometry of the four probes and the material's shape are crucial for accurate resistivity calculation. For thin films, a specific geometric correction factor is applied to the calculated resistance to obtain the sheet resistance. For bulk materials, the resistivity is then derived from the sheet resistance and the film thickness, or directly calculated using a different geometric factor for bulk samples.

This technique is widely applied in semiconductor research and industry for characterizing the electrical properties of silicon wafers, thin-film deposition, and evaluating doping levels. It is also used for measuring the resistivity of conductive inks, pastes, and other solid materials. The simplicity and effectiveness of the four-point probe method make it a standard tool for material characterization where non-destructive, precise resistivity measurements are required.