A carbon nanotube transistor and method of manufacturing a carbon nanotube transistor is disclosed. The carbon nanotube transistor includes a carbon nanotube on a substrate, a gate electrode deposited on the carbon nanotube, and at least one of a source electrode and a drain electrode deposited on the carbon nanotube and separated from the gate electrode by a space region. The carbon nanotube is doped at the gate electrode an in the space region to form a p-n junction.