Computational designing of graphitic silicon carbide and its tubular forms

By employing density-functional theory calculations we predict graphitic and tubular forms of silicon carbide (SiC) and proposes their synthesis. The present calculations suggest that the metastable SiC tubes can be synthesized by using a technique of extreme hole injection [J. M. Schön, Ch. Kloc, and B. Batlogg, Nature (London) 406, 702 (2000); 408, 549 (2000)]. This method is in contrast to the idea to synthesize new-tubular forms with a usage of a carbon nanotube as nucleation seed. Furthermore, the strain energies of SiC nanotubes are lower than those of the carbon nanotubes. The calculated band gaps of the investigated SiC tubes are either direct or indirect depending on the helicities. We expect that the SiC tubes with direct band gaps can be applied as nanoscale optoelectronics devices with strong oscillator strengths.