Molecular dynamics simulation of silicon nanowires with oxide layers under uniaxial tension

The size-dependent brittle-to-ductile transition (BDT) of silicon is an important scientific topic, but its underlying mechanism is still unclear. Silicon nanostructures such as nanowires have been widely used in electronics and optoelectronics applications and have also been used to study the BDT phenomenon of silicon in both experiments and simulations. While silicon is spontaneously oxidized when exposed to air, most of the previous simulation studies have neglected the effect of oxide layers on BDT. In this work, we employ the molecular dynamics (MD) simulation method to study the influence of oxide layers on the BDT of silicon nanowires under uniaxial tension loading. The oxide layers are created by inserting oxygen atoms into the Si-Si bonds from the nanowire surface and several key factors such as nanowire diameter, thickness of oxide layers, temperature, and strain rate are considered. The MD simulation results reveal the effect of oxide layers on the plastic deformation of silicon nanowires and elucidate its atomic-scale mechanisms.