Investigate the mechanical properties of Si/Ge (Ge/Si) core-shell nanowires: A molecular dynamics study

Abstract

Nanowires (NWs) have been used increasingly in practice due to their outstanding mechanical, physical, and chemical properties. In this paper, we use the molecular dynamics (MD) method to investigate the mechanical properties of NWs (Si/Ge, Ge/Si) with a core-shell structure under the axial tensile strain along the <100>/{100} direction. Our results show that the strength and elastic modulus of Ge/Si and Si/Ge NWs depend on the composition and size of the core/shell crosssection. The strength and strain of Ge/Si NW decrease with increasing the size of the core crosssection because of the lattice mismatch between two layers of core/shell materials. The elastic modulus of Ge/Si NWs increases with the increasing the size of the core cross-section, while the elastic modulus of the Si/Ge NW decreases. In addition, the theoretical strength and elastic modulus of Ge/Si NWs reduce with the growth of the temperature. Furthermore, we also investigate the effect of strain rate on the mechanical properties of the Ge/Si NWs. The obtained results of the study provide the intrinsic properties of the core-shell NWs and also help in the design and fabrication of electronic and optical devices based on the Ge/Si NWs.