Understanding the role of silicon oxide shell in oxide-assisted SiNWs growth

• Compositional segregation of Si in SiO layer is observed in Si(111)/SiO interface.
• Diffusion of Si atoms at Si(111)/SiO interface is anisotropic.
• Silicon oxide shell of SiNWs from OAG is SiOy (y < 2) rather than pure SiO2.
• Segregation and anisotropic diffusion of Si plays an important role in SiNWs OAG.

The role of silicon oxide shell in oxide-assisted SiNWs growth is studied by performing ab initio molecular dynamics simulations on the structural and dynamical properties of the interface between crystalline Si(111) surface and disorder SiO thin film. Si atoms in the SiO film tends to aggregate into the vicinity of the Si(111)/SiO interface. In addition, the diffusion of Si atoms at the interface is anisotropic - the diffusion along the interface is several times faster than that perpendicular to the interface. The segregation and anisotropic diffusion of Si atoms at the Si(111)/SiO interface shed interesting light into the mechanism of oxide-assisted silicon nanowire growth.