  Short channel (~80 nm) n-type single-walled carbon nanotube (SWNT)
field-effect transistors (FETs) with potassium (K) doped source and drain
regions and high-k gate dielectrics (ALD HfO2) are obtained. For nanotubes with
diameter ~ 1.6 nm and bandgap ~ 0.55 eV, we obtain n-MOSFET-like devices
exhibiting high on-currents due to chemically suppressed Schottky barriers at
the contacts, subthreshold swing of 70mV/decade, negligible ambipolar
conduction and high on/off ratios up to 10^6 at a bias voltage of 0.5V. The
results compare favorably with the state-of-the-art silicon n-MOSFETs and
demonstrate the potential of SWNTs for future complementary electronics. The
effects of doping level on the electrical characteristics of the nanotube
devices are discussed.
