The stability of the perfect screw dislocation in silicon has been investigated using both classical potentials and first principles calculations. Although a recent study stated that the stable screw was located both in the 'shuffle' and 'glide' sets of {111} planes (Koizumi et al, 2000, Phil. Mag. A, 80, 609), it is shown that this result depends on the classical potential used, and that the most stable configuration belongs to the 'shuffle' set only, in the centre of one ( 101) hexagon. We also investigated the stability of an sp 2 hybridization in the core of the dislocation, obtained for one metastable configuration in the 'glide' set. The core structures are characterized in several ways, with a description of the three dimensional structure, differential displacement maps, and derivatives of the dis-registry.

International audienceLarge-scale atomistic calculations, using empirical potentials for modeling semiconductors, have been performed on a stressed system with linear surface defects like steps. Although the elastic limits of systems with surface defects remain close to the theoretical strength, the results show that these defects weaken the atomic structure, initializing plastic deformations, in particular dislocations. The character of the dislocation nucleated can be predicted considering both the resolved shear stress related to the applied stress orientation and the Peierls stress. At low temperature, only glide events in the shuffle set planes are observed. Then they progressively disappear and are replaced by amorphization/melting zones at a temperature higher than 900 K

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