Functionalization of carbon nanotubes through the chemical binding of atoms and molecules

We present a proposal for altering the electronic properties of single wall carbon nanotubes (SWNT's) through the chemical binding of atoms and molecules. This binding would be performed at Si substitutional defect sites, which would guarantee a high stability to the system. We argue that, by appropriately choosing the atom or radical bound to the Si atom, one can have a greater doping flexibility than has been achieved so far, and can, in principle, engineer transport, optical, or other properties of SWNT's. These conclusions are based on detailed first-principles calculations for a Si-X doped semiconducting (10,0) SWNT, for X={F, Cl, H, CH3, and SiH3}.