Atomic Simulation of the Melting and Mechanical Behaviors of Silicon Nanowires

Abstract

Molecular dynamics simulations using a three-body potential show that the melting and mechanical behaviors of silicon nanowires are strongly dependent on their cross-section area. For the wire with a small cross-section area, rearrangements of surface atoms greatly affect thermal stability in a relatively low temperature regime. For these wires with a relatively large area, while some surface atoms adjust their positions, most of the interior atoms hold their tetrahedra packing patterns. At a high temperature, the accumulation of structural disorder can quickly extend into the entire wire, which resembles the melting of the bulk phase. By applying the uniaxial tensile, these silicon nanowires present the typical mechanical behavior of plastic materials. The atomic local stress in the necking region is apparently larger than that outside of the necking region. As the cross-section area becomes large, both the yield strength and tensile strength increase. With the increasing temperature, the elasticity decreases significantly.