Subsurface nanocracking in monocrystalline Si (0 0 1) induced by nanoscratching

This paper investigates the nanocracking in the subsurface of monocrystalline Si (0 0 1) after nanoscratching at ambient temperature. It was found that a nanoscratching produced a surface groove with shallow dents and a phase transformation zone beneath the surfaces. Subsurface nanocracks emanated from the bottom of the transformation zone with similar penetration depths, but different nanocracks have different crack opening displacements. It was identified that nanocracking could be activated at the intersection of slip bands. A number of slips activated on the {1 1 1} planes were found at the regions near the deflected crack paths and around the crack fronts. The observed plasticity is consistent with the localized lattice mismatch across both sides of a crack along its propagation. The high shear stresses induced by nanoscratching is thought to be responsible for the generation of the crystal defects which could have a shielding effect on the crack tips.