Various kinds of individual CNTs and meta-nanotubes (C60@SWCNT, Co@SWCNT, SWCNTs doped with H2SO4, …) are contacted according to a FET device configuration, either in Toulouse thanks to the RTB platform facility or under partnership, in order to study electronic behavior, magneto-transport, and charge-transfer effects. Among other results : the discrepancy in the Raman response of individual versus bundled DWCNTs was revealed, and why the conductance behavior of individual SWCNTs upon doping is the opposite from that of SWCNT mats was explained ; charge transfer in peapod system was found to occur only when the containing SWCNT is of semi-conducting type ; contained C60-chains shorter than the source-drain distance may behave as NEMS resonators ; short, encapsulated Co nanocrystals behave as nanomagnets that couple electronically with the containing SWCNT and generate conductance jumps related to magnetization reversion events.
Conductance versus gate potential for an individual semi-conducting SWCNT contacted in FET configuration. Step 1 : pristine SWCNT exhibits the regular hysteretic behavior ; Step 2 : doping with H2SO4 induces a metallic behavior, however with a lower conductance ; Step 3 : semi-conducting behavior is restored from dedoping ; Step 4 : original, higher conductance value is restored from exposure to air, while the semi-conducting behavior is maintained. Conductance jump from Step 3 to Step 4 is explained by the adsorption of O2 molecules which by-pass the Schottky barrier at the SWCNT/metal contact interface ; conductance drop from Step 1 to Step 2 shows that the by-pass effect by O2 molecules already exists in the starting configuration, but that H2SO4 is successful in removing the adsorbed species.