  High performance p- and n-type single-walled carbon nanotube (SWNT)
field-effect transistors (FETs) are obtained by using high and low work
function metals, Pd and Al as source/drain (S/D) electrodes respectively. Ohmic
contacts made to chemically intrinsic SWNTs, with no or small Schottky barriers
(SB), afford high ON-state currents up to 20 uA per tube. The lack of
significant Fermi-level pinning at the nanotube-metal interfaces allows for
fine-tuning of the barrier heights for p-and n-channel conductions by changing
the contact metals. The air-stable p- and n-FETs thus obtained can be used for
complementary nanoelectronics, as demonstrated with the fabrication of an
inverter. Other important issues regarding nanotube FETs including hysteresis,
OFF-state leak currents, choice of nanotube diameter, and threshold voltage
control are discussed.
