Correction factor for resistivity and Hall mobility measurement of two-layer structures by spreading resistance techniques

The spreading resistance of a circular disc contact located on a two-layer semiconductor structure, and its relative change due to magnetic field has been determined, with the magnetic field perpendicular to the contact face, and with the physical magnetoresistance zero in both layers. The correct value of the spreading resistance differs from the result obtained by the usual approximation, especially if the contact diameter is comparable with the thickness of the upper layer. The conditions are given when the relative change in resistance due to the magnetic field is determined by the mobility in the upper layer only. The results show the applicability of the spreading magnetoresistance technique in determining the Hall mobility in a two-layer structure.