A reliable method to grow vertically-aligned silicon nanowires by a novel ramp-cooling process

► By using a ramp-cooling process to nucleate Si seeds on Si (1 1 1) based on the principle of liquid phase epitaxy (LPE), almost 100% vertically-aligned SiNWs can be reliably achieved on Si (1 1 1). ► The degree of vertical alignment is highly dependent on the cooling process. ► The percentages of vertically-aligned SiNWs are 30%, 55%, 70% and almost 100% for the cases without ramp cooling and with cooling at the rates of 50 °C/min, 30 °C/min and 10 °C/min, respectively.