Theoretical study of kinks on screw dislocation in silicon

Abstract

Theoretical calculations of the structure, formation and migration of kinks on a non-dissociated screw dislocation in silicon have been carried out using density functional theory calculations as well as calculations based on interatomic potential functions. The results show that the structure of a single kink is characterized by a narrow core and highly stretched bonds between some of the atoms. The formation energy of a single kink ranges from 0.9 to 1.36 eV, and is of the same order as that for kinks on partial dislocations. However, the kinks migrate almost freely along the line of an undissociated dislocation unlike what is found for partial dislocations. The effect of stress has also been investigated in order to compare with previous silicon deformation experiments which have been carried out at low temperature and high stress. The energy barrier associated with the formation of a stable kink pair becomes as low as 0.65 eV for an applied stress on the order of 1 GPa, indicating that displacements of screw dislocations likely occur via thermally activated formation of kink pairs at room temperature

Dislocation motion in silicon: the shuffle-glide controversy revisited

“…Finally, the main factor comes from the large difference between migration energies. While W m is large for partials, due to complex reorganization of atomic bonds [24], it is at least one order of magnitude lower for the screw dislocation because in that case, kink migration occurs by breaking and formation of a single highly stretched bond [22]. Therefore, it is simply the inclusion of migration energies that drastically changes the results compared to the Duesbery and Joós model.…”

“…For non-dissociated dislocations, to our knowledge, no experimental data are available for kinks. Nevertheless, kinks on a non-dissociated shuffle screw dislocation have been recently investigated by means of first principles and atomistic potential simulations, taking advantage of the Nudged Elastic Band method [22]. These calculations indicated that the kink formation energy ranges from 0.90 eV to 1.36 eV, whilst the migration energy is very low, and ranges from 20 meV to 160 meV.…”

“…On the basis of our recent results concerning shuffle screw dislocations [22], and the available data for partial dislocations, we have shown that the model proposed by Duesbery and Joós of a stress driven transition between shuffle and glide dislocations [1] was not conclusive. Several possible scenarios are proposed as alternative explanations, and discussed in relation with available experimental and theoretical results.…”

“…[17] [4]. For the non-dissociated screw, the average (1.13 eV,0.09 eV) of the calculated values [22] are used. According to Hirth and Lothe [3], the energy for the nucleation of a kink pair is…”

Dislocations and Plastic Deformation in MgO Crystals: A Review

“…The further propagation of the kinks along the dislocation line is responsible for the glide of the whole dislocation. The theoretical description of dislocation motion involving the kink-pair mechanism was successfully applied to the understanding of elemental deformation processes (see, for instance, [81]) in several materials, including bcc metals [82][83][84][85][86][87][88][89], covalent materials such as silicon [90][91][92] and ionic materials [93][94][95], including MgO [23].…”