Alternative vapor–liquid–solid process in Au-assisted growth of silica nanowires

• Silica nanowires were grown using Si wafer coated with a thick Au film as a catalyst.
• The nanowires have Au particles inside them, different from those reported.
• An alternative vapor–liquid–solid process for the nanowire growth is presented.

We report the growth process of silica nanowires (NWs) grown by using a thick Au film as a catalyst, and suggest an alternative vapor–liquid–solid mechanism for NW growth. The silica NWs were grown by high-temperature annealing of silicon substrates coated with an Au film measuring either 20 nm or 60 nm thick in a N2 atmosphere. A number of Au particles were observed inside the NWs, unlike NWs grown a single Au particle at their top. The results are attributed to the push-up growth of NWs by the continuous formation of silicon oxide on the top and/or side surfaces rather than underneath of the eutectic liquid Au–Si alloy suggested in the conventional vapor–liquid–solid process.