Strain distribution around SiO₂/Si interface in Si nano wires: A molecular dynamics study

We have performed three-dimensional molecular dynamics simulations to investigate strain and stress distributions in silicon nanostructures covered with thermal oxide films, by using our original molecular force field for Si, O mixed systems. We have modeled a wire-shaped nanostructure by carving a Si(001) substrate, and then an oxide film with a uniform thickness was formed by inserting oxygen atom into Si-Si bonds from the surface. The simulation results show that a compressive stress is concentrated on the oxide region in the vicinity of the side SiO₂/Si interface of the nanowire. At the top interface, there is also a compressive stress in the [110] direction, whereas the [001] component of the normal stress tensor is almost relaxed. These results suggest that the oxidation is strongly suppressed at the side faces of the silicon nanowire.