Long-range Tersoff potential for silicon to reproduce 30° partial dislocation migration

Abstract

Dislocation in silicon has been studied from atomistic viewpoints for many years. It is widely acknowledged that the bond-order Tersoff potential does not reproduce the dislocation dynamics. Addressing the abovementioned shortcoming remains challenging for over three decades. We have developed a new long-range Tersoff potential to reproduce the 30° dislocation dynamics in silicon. We also clarified that the first-neighbor cutoff distance of the original Tersoff potential inhibited the smooth breaking and formation of bonds within the dislocation cores, resulting in non-smooth reaction pathways during kink formation and migration. Consequently, we incorporated a long cutoff distance of 4.5 Å, corresponding to the third-neighbor distance. We also modified the distance-difference term of the Tersoff potential to eliminate an artificial energy increase attributed to the long-range cutoff. The developed potential accurately reproduced the stacking fault energy and the activation energies of kink nucleation and migration, leading to a smoother reaction pathway than the original Tersoff potential. The stacking fault energies of our potential and the original Tersoff potential were 74 and 0 mJ/m2, respectively. The activation energies of kink formation, left kink migration, and right kink migration were 1.09, 0.97, and 0.68 eV, which are closer to the experimental values than those of the original Tersoff. We also confirmed the smooth movement of partial 30° dislocations using molecular dynamics simulation. Our developed potential could contribute the microscopic studies of dislocation in silicon.