Water-vapor-enhanced growth ofGe–GeOx core–shellnanowires and Si1−xGexOy nanowires

Abstract

The effects of moist Ar on the growth ofGe–GeOx core–shellnanowires (Ge–GeOx NWs) and Si1−xGexOy nanowires (SiGeONWs) on Si substrates without adding a metal catalyst via the carbothermal reduction ofGeO2 powdersat 1100 °C were studied. No significant nanowires were grown in dry Ar at a flow rate of 100–300 sccmuntil a bit of water in the range of 0.5–2 ml was loaded into the furnace. More water suppressedthe growth of nanowires because of the exhaustion of more graphite powder. The growth ofGe–GeOx NWs and SiGeONWs follows the vapor–solid and vapor–liquid–solid processes, respectively.The present study showed that the water vapor serves as an oxidizer as well as a reducer at1100 °C in enhancing the growthof SiGeONWs and Ge–GeOx NWs, respectively. The growth mechanisms ofGe–GeOx NWs and SiGeONWs are also discussed.