The three-dimensional structure of crack tip dislocations in single crystal silicon was observed by combining high-voltage electron microscopy and tomography. It was revealed that dislocations cross-slipped proximal to the crack tip even in the initial stages of plastic deformation. The local stress intensity factor along the crack front was calculated by taking into account the experimentally determined dislocation character. Based on these observations and calculations, a model to account for the sequential multiplication of dislocation sources along the crack front is proposed.

Punched-out dislocations emitted from an octahedral oxide precipitate in single-crystal silicon were investigated using high-voltage electron microscopy and tomography (HVEM-tomography) to understand the mechanism of softening caused by the oxide precipitates. In the present paper, direct evidence of the transition of a punched-out prismatic dislocation loop to a slip dislocation is presented. The punched-out dislocation grows into a large matrix dislocation loop by absorption of interstitial atoms, which were produced during oxide precipitation.