Atomic-scale characterization of silicon diffusion on carbon nanotubes

Adsorption and diffusion of silicon on the exterior surface of carbon nanotubes are crucial for the growth of silicon carbide nanotubes (SiCNTs) from carbon nanotubes. We have carried out first-principles calculations to explore these processes. We found that a silicon atom prefers to be adsorbed at the bridge site above a C−C bond tilted to the tube axis with binding energy of 1.29−1.61 eV. The adsorbed silicon atoms have high mobility with diffusion energy barriers less than 0.06 eV. The energetically favorable diffusion paths are oriented along the tube axis.