Arrayed and entangled silicon nanowires using Au nanoparticle catalysts prepared by pulsed laser-induced dewetting

The use of pulsed laser-induced dewetting (PLiD) is reported as a novel approach in the fabrication of Au nanoparticle (NP) catalytic arrays for the growth of Si nanowires (NWs) by chemical vapor deposition using SiCl4 in the presence of H2. On polished Si substrates, PLiD generates Au NP catalysts with long-range order and narrow size distributions. It has been shown that the monodispersed distribution of Au NPs provides consistent diameter control of the as-grown Si NWs. A systematic exploration of the Si NW synthesis time, temperature, and gas flow rates illustrates a level of tunability in terms of morphology, be it arrayed or entangled Si NWs, with varying experimental parameters. An investigation of the effect of growth temperature also showed that Si NWs can be synthesized at temperatures as low as 700 degrees C when using SiCl4 as the precursor. The use of porous Si substrates enabled direct observation of the diameter-dependent growth due to the simultaneous presence of three Au NP size distributions. Growth from the small- and medium-sized Au NP catalysts occurred first, followed by that from the large-sized Au NPs, which was only observed at extended times or high SiCl4 flow rates. The delayed onset of growth from the large-sized Au NPs is due to the longer time to achieve Si super-saturation of larger catalyst NPs. The morphology and diameter control of the as-grown Si NWs reported in this work makes this approach potentially useful toward applications such as nanoelectronics, sensors, and lithium ion battery electrodes depending on the desired morphology.