Growth of single crystal GaAs nanowires by a surface diffusion-mediated solid-liquid-solid process

A facile route to synthesize GaAs nanowires by simply heating Au-coated GaAs substrates to 700 °C under vacuum (～10 ^?3 Torr) was developed in this study. Detailed structural analyses showed that ultrathin single crystal GaAs nanowires with an average diameter of ～15 nm were grown outward from the Au metal droplets remaining on the surface of the GaAs substrate. On the other hand, the substrate surface region contacting the metal layer became porous, and the depth of the porous layer increased with increasing processing time. Based on these results, it was concluded that the nanowires were grown by a solid-liquid-solid process involving the surface diffusion of adatoms from the underlying solid substrates to the Au liquid droplets.