PN junction and band to band tunneling in carbon nanotube transistors at room temperature.

We demonstrate band to band tunneling (BTBT) in a carbon-nanotube (CNT) field effect transistor. We employ local electrostatic doping assisted by charged traps within the oxide to produce an intramolecular PN junction along the CNT. These characteristics apply for both metallic (m-CNTs) and semiconducting (SC-CNTs) CNTs. For m-CNTs we present a hysteretic transfer characteristic which originates from local electrostatic doping in the middle segment of the CNT. This controlled doping is reversible and results in formation and destruction of a PN junction along the CNT channel. For SC-CNTs we observe BTBT, and analysis based on the WKB approximation reveals a very narrow depletion region and high transmission probability at the optimal energy bands overlap. These results may assist in developing a non-volatile one-dimensional PN junction memory cell and designing a tunneling based field effect transistor.