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 mieroelectronie devices based on the nanowires.