Atomic modes of dislocation mobility in silicon

Mechanisms of partial dislocation mobility in the 111 glide system of silicon have been studied in full atomistic detail by applying novel effective relaxation and sampling algorithms in conjunction with the Stillinger-Weber empirical interatomic potential and simulation models of up to 90000 atoms. Low-energy pathways are determined for the generation, annihilation and motion of in-core defects of the 30°-partial dislocation, specifically, the individual left and right components of a double-kink, an antiphase defect (APD), and various kink-APD complexes. It is shown that the underlying mechanisms in these defect reactions fall into three distinct categories, characterized by the processes of bond-breaking, bond switching, and bond exchange, respectively. The quantitative results reveal a strong left-right asymmetry in the kinetics of kink propagation and a strong APD-kink binding; these have not been recognized previously and therefore hold implications for further experiments. The present work also demonstrates the feasibility of the atomistic approach to modelling the kinetic processes underlying dislocation mobility in crystals with high Peierls barriers.