The growth mechanism of silicon nanowires synthesized with or without a metal catalyst via chemical-vapor-deposition (CVD) is discussed by using a developed vapor-liquid-solid and novel sulfide-assisted growth models, respectively. The metal catalyst plays an important role on the catalytic growth. However, the growth of silicon nanowires with sulfide is chiefly affected by the compound decomposition, gas stream, and temperature difference. Silicon nanowires fabricated with metal can be self-organized while a large scale of samples can be achieved with metal-free catalyst. The growth mechanism comparison between metal-and non-metal assisted methods for synthesizing silicon nanowires will supply a beneficial help in deepening the understanding of crystal procedure and improving the sample quality. (c) 2007 Elsevier B.V. All rights reserved.