Molecular dynamics study on the fracture behavior of SiGe nanowire with twist grain boundary under tension

Abstract Crystalline SiGe combining the excellent properties of silicon and germanium plays a key role in modern electronics and optoelectronics technology. In contrast to the extensive researches on electronic and photoelectric properties, here we turn the attention on the mechanical property. By using the molecular dynamics simulations, the fracture behaviors of the [001], [110] and [111] orientated SiGe nanowire with and without twist grain boundary are investigated in the tension process. The results reveal that the twist grain boundary play an important role in the mechanical property of SiGe nanowire as it can inhibit the dislocation atoms from moving along the axial orientation. The fracture behavior of the SiGe nanowire with twist grain boundary is sensitive to the twist angle, radius and temperature. Both the Young’s modulus and maximum stress decrease as the twist angle increases from 8° to 19° or the temperature increases from 50 K to 600 K, while they are enhanced as the radius of nanowire increases. As for the fracture strain, it changes slightly with the radius of nanowire, but decreases with the increasing twist angle and temperature. Interestingly that, the fracture behavior occurs at the twist grain boundary regardless of the twist angle, radius and temperature. Our studies enrich the knowledge of mechanical characteristic of SiGe nanowire with twist grain boundary, which paves the way for processing and device design.