Method for Hall Mobility and Resistivity Measurements on Thin Layers

Abstract

A method for measuring Hall mobility and resistivity in thin layers of semiconducting materials uses four contacts near the center of a sample that is large in comparison to the contact spacing. The measured value of the Hall coefficient is independent of the relative positions of the contacts. For resistivity measurements the contacts have to lie on a circle; the error due to a 10% deviation from this condition is 3%. If the contact spacing is$\frac{1}{10}$ of the smallest sample dimension the Hall coefficient is accurate to 2.5% and the resistivity measurement to 5.5%. Where it is not possible to make the sample large in comparison to the contact spacing, a circular sample and a square array of contacts is proposed. Arrangements which do not fit either case but closely approach both can be treated by first using the infinite sheet method and then correcting for the finite size of the sample by the circular sheet method. These methods may be useful where it is not convenient to form either Hall bridges or contacts to the edge of the sample, as in the van der Pauw method. Measurements on epitaxially grown layers might be carried out by this method.