First-principles Study On SiC Nanowires/Single-walled Nanotubes Core/Shell Heterostructures

Since single-walled nanotubes are one-dimensional nano-materials with hollowstructures, they can be used as new templates for synthesizing one-dimensionalnano-materials, for example, we can fill some materials into carbon nanotubes by useof the capillarity phenomenon, thus synthesize one-dimensional nano quantum wireswith special properties (such as magnetism, superconductivity). Filling the innercavities of carbon nanotubes with a wide varity of materials (Ag, Ni, Co, Se, S, Sb,and Ge) was also extensively investigated. If we combine the single-walled nanotubeswith β-SiC nanowires to form nano coaxial cable, the physical (such as mechanicaland electronic) properties may be improved, which could lead to the importantapplications in nanotechnology for the new nano-materials, e.g. nanoscalmultiterminal electronic devices and light-emiting diode. Recently, Mikhael et al. hadsuccessfully synthesized the SiC/carbon nanotube core/shell structure, which enablethe research of the β-SiC/single-walled nanotubes coaxial cable heterostructure to bepossible. More interestingly, they found the atomic migration rate on the β-SiCnanowires surface coated by carbon nanotubes is higher than that without carbonnanotubes, which hence makes our studies on the electronic properties of theβ-SiC/single-walled nanotubes core/shell structure meaningful.In this paper, we studied the structural and electronic properties of β-SiC/single-walled nanotubes core/shell structure using first-principles methods. It isfound that core-shell heterojunction structures, formed by SiC nanowires coated witheither metallic or semiconducting single-walled nanotubes, show metallic characters.The metallicity of the heterojucntions is contributed by the nanotubes and the surfaceatoms of SiC nanowires. The metallicity of the SiC nanowires is determined by itsstructure. However, the metallicity of the metallic (15,0) and semiconducting (16,0)carbon nanotubes results from not the deformation of the carbon nanotubes, but thecharge transfer between carbon nanotubes and SiC nanowires. Similarly, themetallicity of the single-walled boron nitride nanotube also originates from the chargetransfer between carbon nanotubes and SiC nanowires. Our results provide a certaintheoretical foundation for the application of the β-SiC/single-walled nanotubescore/shell heterostructures.