The first experimental evidence was presented for the dissociation of screw dislocations at (001) low-angle twist boundaries. By using high-resolution electron microscopy and weak-beam transmission electron microscopic techniques, it was found that the grain-boundary screw dislocations, with b = ½<110>, could dissociate into two 30º partials on the (1¯11) plane. These formed an intrinsic stacking fault, as did lattice screw dislocations of the glide set. Upon dissociation, one partial dislocation stood off the grain-boundary plane. However, some segments of the grain-boundary screw dislocations could remain undissociated. An atomic model was proposed for the undissociated screw dislocation core, as well as a mechanism for its transformation into cores of individual 30º partials upon dissociation. The model was based upon classical molecular dynamics simulations, and an empirical interatomic potential. The model aided the understanding of electron microscopy results.

Dissociation of Screw Dislocations in (001) Low-Angle Twist Boundaries - a Source of the 30º Partial Dislocations in Silicon A.Y.Belov, R.Scholz, K.Scheerschmidt: Philosophical Magazine Letters, 1999, 79[8], 531-8