 The growth of template nanowires, silicon deposition and nanowire etching, and consequently the geometry of resulting Si nanotubes, can be accurately controlled in the second method; however, the smallest inner diameter is limited by tens of nanometers.The conventional vapor-liquid-solid (VLS) and solid-liquid-solid (SLS) mechanisms are favorite techniques to grow one-dimensional silicon nanostructures.However, they usually incorporate only one type of metal as catalyst and therefore can not be used for growing tubular (hollow) silicon nanostructures.