Control of surface migration of gold particles on Si nanowires.

On the surface of silicon nanowires (SiNWs) synthesized by gold (Au)-catalyzed chemical vapor deposition (CVD), Au particles 5-20 nm in diameter are formed if the growth conditions are within a specific range. We studied the mechanism of Au particle formation by growing SiNWs under different conditions, specifically by dynamically changing the growth parameters during the growth process. We show that insufficient supply of Si source to the Au-Si eutectic on top of the SiNWs enhances the migration of Au atoms on the surface of SiNWs in the form of Au-Si eutectic, which is precipitated on the surface as Au particles during cooling. We also show that using Au-Si eutectic on the surface of SiNWs as a catalyst enables one-step growth of branched SiNWs.