Contacts shielding in nanowire field effect transistors

Conductive metallic contacts can significantly affect the operation of field effect transistors fabricated starting from semiconductor nanowires deposited on a dielectric substrate. Screening effects can also lead to systematic errors in the estimates of transport parameters obtained on the basis of simple uniform capacitive models. We study the role of contacts in both back- and lateral-gate transistor geometries and provide rules of thumbs to predict screening effects in real devices. Additionally, we show how the contacts influence charge density profiles within the wire, focusing in particular on their evolution when transistors nonlinear properties are addressed.