Atomic scale mechanisms and brittle to ductile transition at low size in silicon

Abstract

Molecular dynamics (MD) simulations of silicon nanowires (NW) tensile deformation were performed. They reveal a great variety of behaviors, which are rationalized thanks to a diagram highlighting the sequences of elementary mechanisms. In particular, MD simulations show that cavity formation inside the NW can occur through dislocations interactions. To quantify the brittle/ductile character of the NWs for each tested conditions, we define a ductility parameter which is extracted from the simulation output. Its variation suggests that the brittle to ductile transition (BDT) at low size is not sharp, conversely to the well-known BDT for bulk silicon.