Carbon nanotube p-n junction diodes

We demonstrate a single-walled carbon nanotube $p\text{-}n$ junction diode device. The $p\text{-}n$ junction is formed along a single nanotube by electrostatic doping using a pair of split gate electrodes. By biasing the two gates accordingly, the device can function either as a diode or as an ambipolar field-effect transistor. The diode current–voltage characteristics show forward conduction and reverse blocking characteristics, i.e., rectification. For low bias conditions, the characteristics follow the ideal diode equation with an ideality factor close to one.