Phase Transformation Dependence on Initial Plastic Deformation Mode in Si via Nanoindentation

Silicon in its diamond-cubic phase is known to phase transform to a technologically interesting mixture of the body-centred cubic and rhombohedral phases under nanoindentation pressure. In this study, we demonstrate that during plastic deformation the sample can traverse two distinct pathways, one that initially nucleates a phase transformation while the other initially nucleates crystalline defects. These two pathways remain distinct even after sufficient pressure is applied such that both deformation mechanisms are present within the sample. It is further shown that the indents that initially nucleate a phase transformation generate larger, more uniform volumes of the phase transformed material than indents that initially nucleate crystalline defects.