Carbon nanotube single-hole transistors operating at room temperature were realized. To obtain large charging energy, a 25-nm-long carbon nanotube channel was formed by shadow evaporation for small gate capacitance and an insulator was inserted between the channel and electrodes for small tunnel capacitances. A significantly small gate capacitance (0.06 aF) and a small tunnel capacitance (0.3 aF) were obtained. The estimated charging energy of a carbon nanotube single quantum dot was 108 meV. Drain current oscillation as a function of gate voltage was clearly observed while typical p-type field effect transistor characteristics were obtained for the device without insulator. These results indicate that the small tunnel capacitance is necessary for the room-temperature-operating carbon nanotube single-charge transistors.
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