Atomic structure of dislocation kinks in silicon

Abstract

We investigate the physics of the core reconstruction and associated structural excitations (reconstruction defects and kinks) of dislocations in silicon, using a linear-scaling density-matrix technique. The two predominant dislocations (the (Formula presented) and (Formula presented) partials) are examined, focusing for the (Formula presented) case on the single-period core reconstruction. In both cases, we observe strongly reconstructed bonds at the dislocation cores, as suggested in previous studies. As a consequence, relatively low formation energies and high migration barriers are generally associated with reconstructed (dangling-bond-free) kinks. Complexes formed of a kink plus a reconstruction defect are found to be strongly bound in the (Formula presented) partial, while the opposite is true in the case of (Formula presented) partial, where such complexes are found to be only marginally stable at zero temperature with very low dissociation barriers. For the (Formula presented) partial, our calculated formation energies and migration barriers of kinks are seen to compare favorably with experiment. Our results for the kink energies on the (Formula presented) partial are consistent with a recently proposed alternative double-period structure for the core of this dislocation. © 1998 The American Physical Society.