Patent ID: 8907690

Claim:
A method of determining an electrical property of a test sample using the so-called Hall effect, the test sample comprising a non-conductive area and a conductive or semi-conductive test area separated by a boundary, wherein the method comprises: providing a test probe comprising a probe body having a planar probe surface, a multitude of probe arms extending from the probe body parallel to the planar probe surface, and a multitude of electrically conductive tips separated by predetermined separation distances, wherein each of the tips is supported by a respective probe arm and is configured to establish electrical contact with the test area, and wherein one of the tips is a current source tip positioned between a first one of the tips and a second one of the tips; providing a magnetic field having field lines passing perpendicularly through the test area; positioning the test probe so as to place the electrically conductive tips in contact with the test area in a first position; determining the shortest distance between the current source tip and the boundary, and between each of the first and second ones of the tips and the boundary; applying a first current to the test sample through the current source tip; measuring a first voltage between the first and second ones of the electrically conductive tips; moving the test probe so as to place the electrically conductive tips in contact with the test area in a second position that changes the ratio of (a) the shortest distance between the current source tip and the boundary to (b) the separation distance between the first and second ones of the electrically conductive tips; applying a second current to the test sample through the current source tip; measuring a second voltage between the first and second ones of the electrically conductive tips; and calculating, on the basis of the first and second measured voltages, an electrical property of the test area.