Bonding characteristics and electronic structures of the contact interfaces between group 13 metals and carbon nanotubes

The electronic density of states (DOS) in carbon nanotubes (CNTs) was recently measured using a structure comprising a single CNT-based field effect transistor (FET) device with an indium (In) electrode. Here, we report the bonding characteristics and electronic structure of the contact interface between Group 13 metals (In, Ga, Al) and (8,0) semiconducting CNTs using first-principles density functional theory (DFT) calculations. Our calculation results showed that CNTs in contact with Al, Ga, or In surfaces display lower binding energies to their contact metal surfaces than that of Pd surface while also preserving their original electronic properties. These results originate from the absence of d-orbitals in the Group 13 metals near the Fermi level, the large equilibrium distance, and the deficiencies in electron charge density at the metal surfaces. This study deepens our understanding of the contact properties between Group 13 metals and CNTs.

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