Au₅Si₂/Si Heterojunction Nanowires Formed by Combining SiO Evaporation with Vapour--Liquid--Solid Mechanism

Crystalline Au₅Si₂/Si heterojunction nanowires (Au₅Si₂/SiNWs) are obtained by thermal evaporating SiO powders on thick gold-coated silicon substrates in a
low vacuum system. Structure analysis of the produced Au₅Si₂/Si heterojunctions is performed by employing a transmission electron microscope (TEM) and a selected area electric diffractometer. The chemical compositions are studied by a energy-dispersive x-ray spectroscope attached to the TEM. A two-step growth model is proposed to describe the formation of the Au₅Si₂/SiNWs. During the first step, crystalline SiNWs are formed via a growth mechanism combining the oxide-assisted growth process with the vapour-liquid-solid model at relatively high temperature. In the second step, the temperature decreases and one segment of the preformed SiNWs reacts with the remnant Au to form single crystalline Au₅Si₂ nanowires by a solid-liquid-solid process. The present work should be useful for the future synthesis and research of high-quality gold silicide nanowires and microelectronic devices based on the nanowires.