Chemical Stability and Electronic Properties of Silicon Doped Carbon Nanotubes: A First Pricniples Study

Density functional theory has been employed to investigate the chemical stability and electronic properties of silicon doped carbon nanotubes. The (5,5) armchair and the (8,0) zigzag carbon nanotubes are doped at different concentration of silicon atoms up to 50%. The results reveal the chemical stability of silicon carbide nanotubes at low silicon concentrations. Both nanotubes are stable with the same number of silicon and carbon atoms (50% concentration). The silicon doping induces a finite bandgap in the metallic armchair carbon nanotube, while reduces the band gap of semiconducting zigzag carbon nanotube. Both nanotubes show a high bandgap at 50% concentration of silicon atoms, where the armchair silicon carbide nanotube can be considered as an insulator with bandgap close to 3 eV.