Overlapping-gate architecture for silicon Hall bar MOSFET devices in the   low electron density and high magnetic field regime
  A common issue in low temperature measurements of enhancement-mode metal-oxide-semiconductor (MOS) field-effect transistors (FETs) in the low electron density regime is the high contact resistance dominating the device impedance. In that case a voltage bias applied across the source and drain contact of a Hall bar MOSFET will mostly fall across the contacts (and not across the channel) and therefore magneto-transport measurements become challenging. However, from a physical point of view, the study of MOSFET nanostructures in the low electron density regime is very interesting (impurity limited mobility [1], carrier interactions [2,3] and spin-dependent transport [4]) and it is therefore important to come up with solutions [5,6] that work around the problem of a high contact resistance in such devices (c.f. Fig. 1 (a)). 
Laurens H. Willems Van Beveren, Kuan Y. Tan, Nai-Shyan Lai, Oleh   Klochan, Andrew S. Dzurak, Alex R. Hamilton
cond-mat.mes-hall cond-mat.mtrl-sci