Tuning from Thermionic Emission to Ohmic Tunnel Contacts via Doping in Schottky-Barrier Nanotube Transistors

Electrical power >1 mW is dissipated in semiconducting single-walled carbon nanotube devices in a vacuum. After high-power treatment, devices exhibit lower on currents and intrinsic, ambipolar behavior with near-ideal thermionic emission from Schottky barriers of height one-half the band gap. Upon exposure to air, devices recover p-type behavior, with positive threshold and ohmic contacts. The air-exposed state cannot be explained by a change in contact work function but instead is due to doping of the nanotube.