Nanotube Light-controlled Electronic Switch

The use of carbon nanotubes for field effect nanoelectronic devices, which has been recently demonstrated, motivates further studies of electrochemical and chemical analogues of nanotube molecular transistors. However, chemical gating is not applicable for modern electronics due to its slow response. Herein we propose a novel molecular electronic device: Nanotube LightControlled Switch (NLCS). The device consists of a carbon nanotube and a switching molecule attached to its surface. The switching molecule consists of two parts: an “anchor” connected to the nanotube sidewall and a charged “tail”. A fast nanomechanical motion of the charged “tail” of the molecule, which is caused by a photon absorption, produces an electrostatic potential modulation, i.e., results in a local electrostatic gating. The variation of the potential of this molecular gate is predicted to lock/unlock the current through the nanotube. The switching molecule charge creates an electrostatic barrier for the nanotube charge carrier motion that causes their scattering and decreases the conductance. We show that the current modulation for a single switching molecule is 40–50%. In order to demonstrate the efficiency of the proposed device we have simulated the modulation of the ballistic conductance of a p-doped zigzag single-wall carbon nanotube (SWNT) by applying a local electric field of a single charge placed near the surface of the nanotube. The nanotube valence band bends due to an external electrical potential of the charge. The external potential creates a barrier for holes