Helical crystalline SiC/SiO2 core-shell nanowires

Helical crystalline silicon carbide nanowires; covered with a silicon oxide sheath (SiC/SiO2) have been synthesized by a chemical vapor deposition technique. The SiC core typically has diameters of 10-40 nm with a helical periodicity of 40-80 nm and is covered by a uniform layer of 30-60 nm thick amorphous SiO2. A screw-dislocation-driven growth process is proposed for the formation of this novel structure based on detailed structural characterizations. The helical nanostructures may find applications as building blocks in nanomechanical or nanoelectronic devices. The screw-dislocation-induced growth mechanism suggests that similar helical nanostructures; of a wide range of materials may be synthesized.