BExtraordinary mobility in semiconducting carbon nanotubes

Semiconducting carbon nanotube transistors with channel lengths exceeding 300 microns have been fabricated. In these long transistors, carrier transport is diffusive and the channel resistance dominates the transport. Transport characteristics are used to extract the field-effect mobility (79 000 cm2/Vs) and estimate the intrinsic mobility (>100 000 cm2/Vs) at room temperature. These values exceed those for all known semiconductors, which bodes well for application of nanotubes in high-speed transistors, single- and few-electron memories, and chemical/ biochemical sensors. Semiconducting carbon nanotubes have been proposed for such nanoelectronics applications as high-speed field-effect transistors (FETs),1 few- or single-electron memories,2 and chemical/biochemical sensors.3,4 The charge-carrier mobility (i.e., conductivity normalized by the density of charge carriers) is crucial to each of these applications. Mobility determines the carrier velocity, and hence switching speed, in FETs. In floating gate memories and chemical/biochemical sensors, nanotube FETs (NT-FETs) will be used to detec