The influence of the surface migration of gold on the growth of silicon nanowires

Silicon nanowires hold great promise as components of tiny electronic devices, but the usual method of growing them is poorly understood. New work shows that excessive cleanliness can actually stunt a nanowire's growth. They are made by the ‘vapour–liquid–solid’ method, in which a tiny liquid droplet of a metal such as gold absorbs silicon atoms from a gaseous precursor molecule. As the droplet saturates with silicon, it grows a solid, cylindrical silicon crystal whose diameter is determined by the size of the droplet. But in conditions of extreme cleanliness, gold atoms from the droplet can migrate over the surface of the growing nanowire, resulting in misshapen structures.