Atomistic modeling of the fracture toughness of silicon and silicon-silicon interfaces

Fracture modeling at the atomic scale is currently an intense area of research because the crack propagation process depends strongly on the description of interatomic interactions. Here we present first the mode-I plane strain quasi-static fracture toughness of single crystal silicon, along four orientations, as obtained using molecular statics simulations with nine empirical potentials. The “best” potential is determined by comparing the fracture toughness and trapping range of the simulations with available experimental data and with results calculated using first-principles molecular dynamics. The choice is buttressed by its ability to predict the effective toughness and propagation direction of a crack subjected to mode-II loading. The best performing potential is then used to investigate the fracture toughness and the role of bond trapping for a crack along the boundary of two silicon crystals belonging to two different tilt families.