Core element effects on dislocation nucleation in 3C-SiC: Reaction pathway analysis

The nucleation of glide-set 90° partial dislocation from a sharp corner in 3C-SiC has been investigated by reaction pathway analysis. We focus on the core element effect and assert that both the stress-dependent activation energy and the athermal strain of C-core dislocation nucleation are higher than those of Si-core, while the gradient of the energy curve for C-core nucleation is lower than the Si-core counterpart, manifesting the greater thermal sensitivity of C-core dislocation. The results indicate that the nucleation of Si-core dislocation is more energy-favorable, while the C-core dislocation would nucleate with thermal assistance under high temperature, which explain the observation of core nature effects on dislocation performance in SiC by previous experiments. Estimation of dislocation nucleation behavior under high temperature has also been conducted. The free energy is obviously reduced at deposition temperature, implicating the much higher occurrence rate of dislocations with both C-core and Si-core during the crystal growth process. Moreover, from the viewpoint of different mobilities of boundary partial dislocations due to the core element effect, the distinct performances of stacking faults with Si-face and C-face exposure on the (0 0 1) surface during film deposition have been discussed, providing a reasonable explanation of our previous observation [1], [2].