Gallium-driven assembly of gold nanowire networks

Nanowire networks of Au–Ga alloy are fabricated at temperatures between 220 and 300°C by application of small drops of liquid gallium to 10- to 100-nm-thick gold films. As the liquid gallium drop spreads and reacts with the gold film, lamellar segregation of gold-rich and gallium-rich regions form fractal-like networks of Au–Ga nanowires connected between gold-rich islands in specific zones concentric to the gallium droplet. The wires are subsequently suspended by wet chemical etching that undercuts the ∼10-nm-thick chromium adhesion layer and the silicon substrate. Suspended nanowires as long as 6μm and as narrow as 35nm diameter have been produced using this method.