Low-temperature Growth of Ge Nanowires by Vapor-Liquid-Solid Chemical Vapor Deposition

This paper reports the growth of the germanium nanowires (Ge NWs) with a single-step temperature method via vapour-liquid-solid (VLS) mechanism in the low pressure chemical vapour deposition (CVD) reactor at 300, 280 and 260°C. The Ge NWs grown at 300°C tend to have a tapered structure and the sidewalls of the nanowires were observed to be decorated with gold. The tapering was caused by the uncatalysed deposition of Ge via CVD mechanism at the sidewalls of the nanowires and significantly minimised at 260°C which leads to the formation of straight and ultra-thin Ge NWs. The sidewalls of the Ge NWs grown at 260°C were also observed not to be decorated with gold. The Ge NWs grown from 0.1-nm-thick Au at 260°C had diameter as small as ~3 nm which offers an opportunity to fabricate high-performance p-type ballistic Ge NW transistor and to realise nanowire solar cell with higher efficiency