Spreading of Liquid AuSi on Vapor−Liquid−Solid-Grown Si Nanowires

Abstract

Vapor-liquid-solid growth of high-quality Si nanowires relies on the stability of the liquid metal seed. In situ transmission electron microscopy shows that liquid AuSi seed spreads along the sidewalls of Si nanowires for some growth conditions. This liquid thin film phase separates to form solid Au clusters as the nanowire is quenched below the solidus temperature. The length that the liquid film spreads from the seed and its thickness can be explained by considering the spreading thermodynamics of droplets on cylinders.

Temperature dependent resistance and cryogenic microwave spectroscopy of Au decorated silicon nanowires

“…After post-growth air exposure, the Au decoration is at the SiNW-SiO 2 interface. As previously reported, [3][4][5] we find this Au sidewall decoration to be CVD condition dependent, in particular related to the relatively low SiH 4 partial pressure used here. This effect can be explained by the interplay of surface energies during VLS based nanowire growth.…”

“…This effect can be explained by the interplay of surface energies during VLS based nanowire growth. 3,6 The inset of Fig. 1(b) shows that this prominent Au sidewall decoration can be removed by post-growth wet etching, but this will only remove the Au-rich sidewall nanoparticles, and any Au still remaining in the nanowire will be unaffected.…”

Advanced core/multishell germanium/silicon nanowire heterostructures: The Au-diffusion bottleneck

“…Note that from Figs. 1(a)-1(h), we show that Au diffusion on the Ge NW sidewalls occurs after growth of the Ge NW core during the ramp up to a temperature that is suitable for Si or Ge shell growth, and is to be distinguished from previously reported high temperature or low pressure NW growth conditions where Au diffusion 7,8 can occur concurrently with NW VLS growth and the NW morphology is adversely compromised. In addition, atomic hydrogen passivation which has been noted to cause dewetting of Au on Si surfaces 9 does not inhibit Au diffusion on the Ge NW surfaces, as deduced from our temperature ramp experiments to the Si growth temperature in H 2 or GeH 4 ambient where in both cases we observed Au diffusion to still occur.…”

Size‐Dependent Surface Migration of Au Alloys on Si Nanowires at Different Cooling Rates

“…SiNWs were successfully grown via a Au catalyst‐assisted VLS mechanism by exploiting the availability, stability, and nontoxicity of Au . The production of SiNWs incorporated into Au alloys is desirable; however, one major problem with this method is the contamination of the sidewalls of the SiNWs by the Au alloy due to the rapid diffusion and migration of Au into Si . The Au contaminations caused by Au migration on the NWs can act as impurities, leading to deep levels in the bandgap and the degradation of electronic properties .…”