Study of Grass Shoot-Shape Silicon Nanowires Grown by Thermal Chemical Vapor Deposition

Grass shoot-shape silicon nanowires (SiNWs) with sharp tip have been successfully synthesized on an n-type Si (111) substrates at temperatures of 700 °C and various times using a thermal chemical vapor deposition (TCVD) technique. Au thin film (~10 nm thick) as catalyst were deposited on Si (111) substrates by a radio frequency magnetron sputtering system. Effect of the growth time on morphology of SiNWs has been reported. The morphologies, growth mechanism, homogeneity and crystalline structure of the nanowires were studied by Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), X-ray diffractometer (XRD) and Raman spectroscopy. SEM images depict morphology of wires in form of nanoneedles (NNs) with base diameter of 60 nm, tip diameter of ∼5 nm and length up to 3 μm. TEM analysis revealed that the nanowires have core-shell structure with Au nanoparticles on the tip. Raman spectrum of as-grown SiNNs exhibited a transverse optical (TO) phonon mode. The obtained results have shown radius and length of the SiNNs increased with increase in growth time.