Ag nanostructures on a silicon nanowire template : Preparation and X-ray absorption fine structure study at the Si K-edge and Ag L3,2-edge

We use X-ray absorption fine structure (XAFS) spectroscopy at the Si K-edge and the Ag L_3,2-edge to monitor the surface chemistry of silicon nanowires. We found that Si nanowires prepared by laser ablation and thermal evaporation are coated with a thick layer of oxides that can be readily removed with a HF solution. HF-refreshed silicon nanowires become a moderate reducing agent and can be used as a nanostructure template upon which silver nanoaggregate deposited reductively from a Ag⁺ aqueous solution, reoxidizing the surface in the process. These results are compared with those of porous silicon.