Effect of surface roughness on elastic limit of silicon nanowires

Effect of surface roughness on deformation mechanism and yielding strength of silicon nanowires under tension are investigated by using molecular dynamics simulation. By varying opening angle and depth of surface notches, different periodic V-type notches models are created on {1 0 0} or {1 1 0} side surfaces to simulate different types of surface roughness. The results show that the presence of rough surface can significantly reduce the initial elastic limit of silicon nanowires. The yield stress of rough wires with a certain cross-sectional size depends on the surface notch depth and is independent of the opening angle. We also investigated the size effect on this notch depth dependence, and observed that the yield stress becomes less sensitive when the wire height increases. In addition, the influence of surface orientation on the surface roughness effect was discussed.