A detailed fractographic analysis of cleavage steps in silicon

Abstract

A detailed analysis of cleavage steps present on fracture surfaces in pure silicon has been carried out using scanning electron microscopy. The results indicate that the mechanisms involved in both the formation of unfractured ligaments, produced when adjacent cleavage facets overlap, and the subsequent fracture of these ligaments to form cleavage steps, are quite complex. Specifically it is shown that, during ligament formation, the local crack fronts are deflected from their preferred (1 1 1) cleavage plane and that the fracture of these ligaments to form cleavage steps occurs in a very complex fashion producing very small microcleavage steps. It is shown that these latter steps are consistent with cleavage along both {1 1 1} and {0 1 1} planes.