Abstract
Three terminal measurements on a carbon nanotube field effect transistor (CNTFET) were carried out in high vacuum and the ambient, and its performance compared. The on-off current ratio, ION/IOFF, were 102 and 105 for devices operated in high vacuum and in ambient air, respectively. Here, we show that the conversion of p-type to ambipolar behavior may largely be attributed to the O2 in ambient doping the single walled carbon nanotubes (SWCNTs) in the active channel which consists of bundles of SWCNTs. Switching behaviour of these devices, with respect to constituent types of SWCNTs in the bundles will be discussed.