Electronic Structure Study of Halogen and Gold Halide Doped Carbon Nanotubes

Achieving high electrical conductivity of carbon nanotubes (CNTs) through doping will facilitate its application in power transmission cable and nanoelectronic interconnects. Here, we report extremely efficient p-doping of CNT using halogen and gold halide molecules. Using ab initio theoretical calculations based on density functional theory, we investigated the effect of dopants, such as I₂ and AuCl_3, on the electronic band structure of semiconducting and metallic CNTs. We found that both I₂ and AuCl₃ introduces states between the first Van Hove singularities of conduction and valance bands. I₂ was reported being an efficient dopant for CNTs. From our calculations, we confirm that large Fermi level shift occurs for both I₂ and AuCl₃ doping. Though the Fermi shift is much larger for AuCl₃ doping. Moreover, transmission function calculations reveal that a few fold increase in available quantum channels exists for AuCl₃ doping compared to I₂ doping. Therefore, gold halide such as AuCl₃ can be a perfect candidate as a dopant molecule of CNTs to produce conductors with ultra-high conductivities.