Nanoscale plastic deformation mechanisms of single crystalline silicon under compression, tension and indentation

Abstract

Mechanical behavior and underlying nanoscale plastic deformation mechanisms of single crystalline silicon under compression, tension and indentation are investigated through molecular dynamics in this work. Simulation results show that phase transformation from diamond cubic Si-I to [Formula: see text]-Sn is responsible for the plastic deformation behavior of Si both under compression and nanoindentation. A stress plateau is observed when the specimen is compressed uniaxially. Si-I to [Formula: see text]-Sn phase transformation has been demonstrated to be responsible for such stress plateau. Periodic boundary condition is found not suitable to study the tensile strength of silicon pillars. A pop-in behavior is observed in the force–displacement curve of nanoindentation. It has been proved that this pop-in region is induced by Si-I to [Formula: see text]-Sn phase transformation. Through tracking the atom stress, shear stress rather than normal stress is revealed to dominate the phase transformation process. During nanoindentation, to exclude size effect the substrate should be larger enough than the indenter.