From Si nanowire to SiC nanotube

Abstract

Si nanowires (NWs), with diameters of about 800 nm and lengths of about 10 μm, previously synthesized by the VLS method with gold catalyst, were carburized at 1,100 °C under methane for conversion into SiC nanostructures. These experiments have shown that Si NWs have been transformed into SiC nanotubes (NTs) with approximately the same sizes. Nanotubes’ sidewall thickness varies from 20 to 150 nm depending on the NTs’ height. These SiC nanotubes are hexagonal in shape and polycrystalline. A model of growth based on the out-diffusion of Si through the SiC layer was proposed to explain the transformation from Si nanowires to SiC nanotubes. This model was completed with thermodynamic calculations on the Si–H2–CH4–O2 system and with results from complementary experiment using propane precursor. Routes for obtaining crystalline SiC NTs using this reaction are proposed.