Interaction of aromatic compounds with carbon nanotubes:: Correlation to the Hammett parameter of the substituent and measured carbon nanotube FET response

We have used field-effect transistor (FET) devices with semiconducting single-walled carbon nanotubes (SWNTs) as the conducting channels to study interactions of aromatic compounds with SWNTs. Electronic detection occurs through charge-transfer effects, monitored as the change of the gate voltage (V-g) dependence of the source-drain current I-sd. For monosubstituted benzene compounds, we find that the shift of the I-sd - V-g characteristic is proportional to the Hammett sigma values (sigma(p)) of their substituents.