Paper NS-WeA9
Spectroscopic Study of the Electron Transport Suppression Phenomenon in Carbon Nanotubes Field-Effect Transistors

Wednesday, November 11, 2009, 4:40 pm, Room L

Carbon nanotubes field-effect transistors (CNFETs) were thought to exhibit exclusive hole transport under ambient atmosphere because of the high potential barrier to electron injection at the electrode-nanotube contact interface. This hypothesis did not hold against a set of new experiments we devised, where ambipolar transport was observed under ambient atmosphere by merely changing the nature of the dielectric used as the substrate. Using controlled atmosphere experiments, we pinpointed the phenomenon responsible for the inhibition of electron transport in CNFETs, and showed it is mainly caused by an electrochemical charge transfer to the aqueous oxygen redox couple. We postulated that intermediates of the redox charge transfer are stabilised at the SiO₂ surface as charged oxygen species leaving a net negative charge at the surface and thus screening the applied gate potential. Focusing on a spectroscopic investigation, we tested the existence of these species. Thermodesorption spectroscopy experiments coupled to reflection-absorption infrared spectroscopy under high vacuum conditions were used to probe the dielectric interface of CNFETs operated under ambient atmosphere prior to insertion into the experimental chamber.