Silicon monoxide clusters: the favorable precursors for forming silicon nanostructures

Using density-functional calculations, we show that the energetically favorable configurations of silicon monoxide clusters (SiO)n for n> or =5 facilitate the nucleation and growth of silicon nanostructures as the clusters contain sp3 silicon cores surrounded by silicon oxide sheaths. The frontier orbitals of (SiO)n clusters are localized to a significant degree on the silicon atoms on the surface, providing high reactivity for further stacking with other clusters. The oxygen atoms in the formed larger clusters prefer to migrate from the centers to the exterior surfaces, leading to the growth of sp3 silicon cores.