Growth mechanisms for atypical forms of silicon nanowires

An investigation was carried out into the growth mechanisms for atypical forms of silicon nanowires (Si-NWs) synthesized using a vapor-liquid-solid growth process assisted by hydrogen radicals. Sn or Au nanoparticles, which act as catalysts during Si-NW growth, were produced by hydrogen radical treatment of Sn or Au thin films covering a silicon substrate. The Si-NWs were synthesized from silane gas excited by hydrogen radicals in the presence of these nanoparticle catalysts. In addition to normal Si-NW structures, atypical forms such as tapered, branched, bent, corrugated and block types, were synthesized. The growth of tapered, branched and bent-type Si-NWs was caused by contraction of the catalytic nanoparticles, adhesion of nanoparticles to the side wall of growing Si-NWs, and non-uniform supersaturation of the nanoparticles with Si, respectively. Growth of corrugated- and block-type Si-NWs was induced by an excess supply of Si atoms to the growing Si-NWs.