First-principles study of contact between Ti surface and semiconducting carbon nanotube

The electronic structure of contact between Ti surface and a semiconducting carbon nanotube is investigated by using first-principles method. The nanotube placed on the Ti surface exhibits obvious cross section distortion and strong chemical bonds form between C and Ti. Our results suggest that the nanotube may become metallic and the electrons can be transferred from the nanotube to the Ti electrode without any electrostatic potential barrier. The results are quite different from those of semiconducting carbon nanotube on Al surface, given that Al and Ti have similar work functions. This difference can explain the unexpected experimental difference between Al-nanotube contact and Ti-nanotube contact.