The growth of small diameter silicon nanowires to nanotrees

In this work we have studied a way to control the growth of small diameter silicon nanowires by the vapour-liquid-solid (VLS) mode. We have developed a method to deposit colloids with good density control, which is a key point for control of the nanowire (NW) diameter. We also show the high dependence of the allowed growth diameter on the growth conditions, opening the door to the realization of as-grown 2 nm silicon NWs. Finally we have developed a smart way to realize nanotrees in the same run, by tuning the growth conditions and using gold on the sidewall of nanowires, without the need for two catalyst deposition steps.