  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)).
