Molecular dynamics simulations of the mechanical properties of crystalline/amorphous silicon core/shell nanowires

摘要

The nanomechanical properties of Si/a-Si core-shell NWs are investigated using molecular dynamics simulations with EDIP model. Under uniaxial compressive and tensile loading, the computed Young's modulus increases as the radius of crystalline core increases and decreases as the thickness of amorphous shell increases. Whereas the critical strains are found to be independent of the size of crystalline cores and amorphous shells. For the nonaxial torsional and bending strains, both torsional stiffness and bending stiffness increase as the thickness of amorphous shell increases and also as the radius of crystalline core increases. In addition, the critical torsion angle rapidly decreases as the thickness of amorphous shells increases and also as the radius of crystalline core increases. However, the critical bending angles are independent of the size of crystalline cores and amorphous shells. These results show that the amorphous shell has significant effects on the mechanical properties of Si/a-Si core-shell NWs under external loadings.