On the origin of preferential growth of semiconducting single-walled carbon nanotubes

Abstract

A correlation is observed between the diameters (d) of single-walled carbon nanotubes and the percentages of metallic and semiconducting tubes synthesized at 600°C by plasma-assisted chemical vapor deposition. Small tubes (d ≈ 1.1 nm) show semiconductor percentages that are much higher than expected for a random chirality distribution. Density functional theory calculations reveal differences in the heat of formation energies for similar-diameter metallic, quasi-metallic, and semiconducting nanotubes. Semiconducting tubes exhibit the lowest energies and the stabilization scales with ∼1/d 2. This could be a thermodynamic factor in the preferential growth of small semiconducting nanotubes. © 2005 American Chemical Society.