Reaction pathway analysis for differences in motion between C-core and Si-core partial dislocation in 3C-SiC

Abstract

Reaction pathway analysis was carried out to investigate the activation energy barriers of Shockley partial dislocation mobility in 3C-SiC. For each partial dislocation, there are two types of dislocations according to which kind of atom, Si or C, comprises the core edge of the dislocation line. In this paper, the partial dislocation is simulated by Vashishta potential functions. Moreover, the activation energy of kink pair nucleation and kink migration are investigated by reaction pathway analysis. The dependence of the activation energy on the driving shear stress is also discussed. The results show that during kink migration, 30° partial dislocations have a lower activation energy barrier than 90° partial dislocation. And, C-core partial dislocations have a higher activation energy barrier than Si-core dislocations for both degrees of partial dislocations during kink migration and nucleation. This conclusion is consistent with the experimental result that Si-core dislocations migrate more readily than C-core dislocations. Furthermore, we found that partial dislocations with larger distance between the dangling bond atoms along the dislocation line have higher activation energy barriers. Based our calculation results, we propose new models to account for the morphological differences in the dislocation lines.

Reaction pathway analysis for the conversion of perfect screw basal plane dislocation to threading edge dislocation in 4H-SiC

“…49) Reaction pathway analysis is based on the nudged elastic band (NEB) method [50][51][52] and is described in references. [42][43][44][45][46][47] The NEB method is efficient for finding the minimum energy path (MEP) between a given initial state and a final state of a transition phenomenon. The MEP is found by constructing a set of images (replicas) of the system between the initial and final states.…”

“…41) In this paper, first we investigate the surface effect on the constriction of partial BPDs to a perfect BPD in the framework of reaction pathway analysis. [42][43][44][45][46][47] We then investigate the surface effect on the cross slip of the perfect BPD. We focus especially on the structural transition of the dislocation core during cross slip.…”

Kink Migration along 30° Si‐Core Partial Dislocations in 4H‐SiC

“…However, in any case, it can be concluded that the activation energy hardly exceeds a few tens of meV which correlates with the theoretical predictions. [34,35] A small difference between kink velocities measured at room and liquid nitrogen temperatures allows assuming that it is even smaller than 10 meV.…”

“…[ 33 ] Thus, from the slight deviation of mobile PD direction from the Peierls potential valleys it was concluded that 30° Si‐core PDs did not move after switching off electron irradiation that allowed to assume that the migration energy of the kinks is too high to migrate at room temperature without excitation. [ 33 ] In contrast, as predicted by theoretical studies, [ 34,35 ] the barrier for the kink migration can be of about 30–60 meV for some core configurations (e.g., symmetrically reconstructed), [ 34 ] i.e., low enough to migrate at room temperature. Besides, as shown in, [ 14,36,37 ] SSFs can expand beyond the irradiated region at distances significantly exceeding the diffusion length that was explained by the enhanced excess carrier transport along SSFs.…”

Reaction pathway analysis for the contraction of 4H-SiC partial-dislocations pair in the vicinity of surface

“…We use the nudged elastic band (NEB) method [26][27][28][29] for the reaction pathway analyses. [30][31][32][33][34][35] This method is efficient for finding the minimum energy path (MEP) between an initial and final state in a transition phenomenon by constructing a set of images (replicas) of the system. The MEP enables us to calculate activation energies.…”