Chemically sensitive Field Effect Transistors of oxide-free silicon nanowires - towards detection of volatile biomarkers of cancer

In this paper we show that oxide-coating of Si nanowires (NWs) limit the response of Si NW field effect transistors (FETs) to their environment, also if the NWs are coated with adsorptive molecular functionality. This behavior is in accord with prior works showing that Si/SiO₂ interface trap and scatters carriers and compensate for the back gate voltage of FETs. Etching-away the SiO₂ and terminating the surface of Si NWs by molecular functionality through stable Si-C bond lead for high-sensitive detection levels of various polar and a-polar vapor compounds at concentration levels down to few tens of ppb. Using an array of molecule-terminated, oxide-free Si NW FETs in an electronic nose configuration allow analysis of complex multi-component (bio) chemical media and good discrimination between simulated patterns of ldquohealthyrdquo and ldquocancerousrdquo breathe.