Synthesis of Si nanowire/nanosheet complexes from CaSi2 crystals by thermal annealing under MnCl2/NH4Cl vapors

Si-based nanowire/nanosheet bundle complexes were synthesized from CaSi2 crystal powders by thermal annealing under MnCl2/NH4Cl vapors. The formation of the complexes is a result of two processes that simultaneously occurred. One is the nanosheet bundle synthesis by Ca-atom extraction from the CaSi2 crystals. Another is the growth of the Si nanowires by thermal annealing using MnCl2. The mixing of these materials resulted in the successful synthesis of the nanowire/nanosheet bundle complexes. In addition to the formation of the complex, nanotubes were also synthesized by bottom-up nanostructure synthesis technique, which resulted by the thermal annealing of the catalytic Mn-related materials under a higher vapor pressure using NH4Cl. The growth mechanism of the nanotubes is discussed based on the inhomogeneous Mn-related catalyst deposition and the surface diffusion of Si atoms.