The first atomistic simulations of orthogonal networks of screw dislocations in this semiconductor were performed in order to investigate the core structures of dislocation intersections. Structural models for the dislocation intersections were proposed, and were investigated by using classical molecular dynamics methods and the empirical interatomic potential of Tersoff. The screw dislocations, with Burgers vector of (a/2)<110>, were assumed to be undissociated, in agreement with experimental data on the atomic structures of synthetic low-angle Si/Si(001) twist boundaries. It was found that the cores of the dislocation intersections were composed of closed characteristic groups of atoms (extended point defects). The structure of these defects depended upon whether the screw dislocation arrays generated twist or shear boundaries. The former had a well-defined energy minimum, with the characteristic groups having a point-group symmetry of 222(D2). The latter exhibited a degeneracy in the number of local energy minima; corresponding to non-symmetrical characteristic groups having differing atomic coordinations.

Atomic structures of dislocation intersections at (001) low-angle twist and shear boundaries in silicon A.J.Belov, K.Scheerschmidt: Philosophical Magazine Letters, 1999, 79[3], 107-14