Rethinking of the silicon nanowire growth mechanism during thermal evaporation of Si-containing powders

• The theory of “oxide-assisted growth” was wrong.
• Si comes from the ejected micron-sized Si or SiO powder particles.
• Al and Cu existed on the quartz tube wall.
• Al could be reduced from alumina tube by H2 in case of alumina tube.
• Si nanowires were seeded by metal-Si eutectic droplets at the tube wall.

Silicon (Si) nanoparticles that are precipitated through the disproportionation of SiO have been regarded as the seeds to the growth of Si nanowires during thermal evaporation of Si-containing powders in quartz or alumina tube without any supply of metallic catalyst. However, compositional scrutiny of the quartz tube after high temperature dwelling reveals traces of metallic aluminum and copper, which are perfect catalysts for Si nanowire seeding and growth. With all due respect, this study prompts rethinking of the seeding and growth mechanism of Si nanowires grown via thermal evaporation of Si-containing powders.