Van der Pauw Experiment, VDX-01

Van der Pauw Experiment, VDX-01

Van der Pauw Set-Up for measurement of resistivity and determination of hall co-effiecients in semiconductor samples.

Introduction

Semiconductor material research and device testing often involve determining the resistivity and Hall mobility of a sample. The resistivity of the semiconductor material is often determined using a four-point probe technique. With a fourprobe, or Kelvin, technique, two of the probes are used to source current and the other two probes are used to measure voltage. Using four probes eliminates measurement errors due to the probe resistance, the spreading resistance under each probe, and the contact resistance between each metal probe and the semiconductor material. Because a high impedance voltmeter draws little current, the voltage drops across the probe resistance, spreading resistance, and contact esistance are very small. One common Kelvin technique for determining the resistivity of a semiconductor material is the van der Pauw (VDP) method. The van der Pauw method involves applying a current and measuring voltage using four small contacts on the circumference of a flat, arbitrarily shaped sample of uniform thickness. This method is particularly useful for measuring very small samples because geometric spacing of the contacts is unimportant. Effects due to a sample size, which is the approximate probe spacing, are irrelevant.

Description of Experimental Set-up