Molecular-dynamics study of energetic cluster impact on silicon

摘要

To investigate the dynamic deformation behavior of silicon induced by the energetic cluster impact at an atomistic level, cluster impact simulations are carried out using molecular dynamics. Clusters are emitted to the silicon (100) surface with external kinetic energies varying from 1 to 10 eV/atom. While a structural phase transformation is identified as the dominant deformation mechanism in silicon due to the increased pressure caused by the energetic cluster impact, its deformation pathway tends to change according to the kinetic energy of cluster. In the lower energy region, the initial diamond structure of silicon is first transformed into the beta-tin structure during the impact process, and then this high-pressure structure is transformed into an amorphous structure after the impact process is completed. This result is very similar to those computed in the quasi-static deformation. On the other hand, amoiphous structures are directly transformed from initial diamond structure in the higher energy region. Additionally, the propagation of the shock-wave is accompanied in this deformation.