Finite Element Analysis on the Influence of Contact Resistivity in an Extraordinary Magnetoresistance Magnetic Field Micro Sensor

In this paper, an extraordinary magnetoresistance (EMR) device made of an InSb/Au hybrid structure was investigated. Those devices have a large potential in becoming a new generation of highly sensitive and cheap magnetic micro sensors. A crucial factor for the performance is the interface between the InSb and Au, which suffers from a certain contact resistivity. The Finite Element Method (FEM) was employed to simulate the current redistribution in the device, under an applied magnetic field. Specifically, the influence of the contact resistivity between the InSb bulk and Au shunt was studied. In a device with optimized geometry and without contact resistivity between the layers of InSb and Au, the EMR effect and the sensitivity show values of 1.89x10(4)% and 0.02%/(10(-4) T), respectively, at 1 Tesla. For values of contact resistivity up to 10(-8) Omega cm(2) the EMR effect is almost constant, while for higher values the EMR effect decreases exponentially. However, the sensitivity of the device does not decrease until 5x10(-6) Omega cm(2) of contact resistivity. Only beyond this value the sensitivity, which in most cases is associated with the performance of the device, will deteriorate.