{\bf To summarize},
in a short review of the C/Si compound and the fabrication of the technologically promising semiconductor SiC by IBS, two controversial assumptions of the precipitation mechanism of 3C-SiC in c-Si are elaborated.
-These propose the precipitation of SiC by agglomeration of \ci{} DBs followed by a sudden formation of SiC and otherwise a formation by successive accumulation of \cs{} via intermediate stretched SiC structures, which are coherent to the Si lattice.
+These propose precipitation of SiC by agglomeration of \ci{} DBs followed by a sudden formation of SiC and otherwise a formation by successive accumulation of \cs{} via intermediate stretched SiC structures, which are coherent to the Si lattice.
To solve this controversy and contribute to the understanding of SiC precipitation in c-Si, a series of atomistic simulations is carried out.
In the first part, intrinsic and C related point defects in c-Si as well as some selected diffusion processes of the C defect are investigated by means of first-principles quantum-mechanical calculations based on DFT and classical potential calculations employing a Tersoff-like analytical bond order potential.
Shortcomings of the computationally efficient though less accurate classical potential approach compared to the quantum-mechanical treatment are revealed.
The study proceeds investigating combinations of defect structures and related diffusion processes exclusively by the first-principles method.
The applicability of the utilized bond order potential for subsequent MD simulations is discussed.
-Conclusions on the precipitation based on the DFT results are drawn.
-In the second part, classical potential MD simulations are performed, which try to directly reproduce the precipitation.
+Conclusions on the precipitation mechanism based on the DFT results are drawn.
+In the second part, classical potential MD simulations are performed, which try to directly reproduce the precipitation process.
Next to the shortcomings of the potential, quirks inherent to MD are discussed and a workaround is proposed.
Although direct formation of SiC fails to appear, the obtained results indicate a mechanism of precipitation, which is consistent with previous quantum-mechanical conclusions as well as experimental findings.
However, barrier heights, which are overestimated by a factor of 2.4 to 3.5 depending on the character of migration, i.e.\ a single step or two step process, compared to the DFT results, are obtained.
Obviously, the EA potential fails to describe \ci{} diffusion yielding a drastically overestimated activation energy, which has to be taken into account in subsequent investigations.
-Subsequent investigations focus on defect combinations exclusively by the first-principles description.
+A series of investigations focuses on defect combinations exclusively by the first-principles description.
These configurations are constructed in such a way as to allow for a quantum-mechanical treatment.
-Investigations of two \ci{} defects of the \hkl<1 0 0>-type for varying separations and orientations state a rather attractive interaction between these interstitials.
+Investigations of two \ci{} defects of the \hkl<1 0 0>-type for varying separations and orientations state a fairly attractive interaction between these interstitials.
The capture radius is found to be rather large compared to other defect combinations.
-Mostly energetically favorable configurations of two interstitials are found.
+For the most part, energetically favorable configurations of two interstitials are found.
This is due to strain compensation enabled by the combination of such defects in certain orientations.
An interaction energy proportional to the reciprocal cube of the distance in the far field regime is found supporting the assumption of \ci{} DB agglomeration.
The energetically most favorable configuration consists of a C-C bond.
% conclusions 2nd part
{\bf Conclusions}
concerning the SiC conversion mechanism are derived from results of both, first-principles and classical potential calculations.
-Although classical potential MD calculations fail to directly simulate the precipitation of SiC, obtained results, on the one hand, reinforce previous findings of the first-principles investigations and, on the other hand, allow further conclusions on the SiC precipitation in Si.
+Although classical potential MD calculations fail to directly simulate precipitation of SiC, obtained results, on the one hand, reinforce previous findings of the first-principles investigations and, on the other hand, allow further conclusions on the SiC precipitation in Si.
Initially, quantum-mechanical investigations suggest agglomeration of \ci{} defects that form energetically favorable configurations by an effective stress compensation.
Low barriers of migration are found except for transitions into the ground-state configuration, which is composed of a strong C-C bond.
This way, C can be easily rearranged in order to end up in a configuration of C atoms that occupy substitutionally the lattice sites of one of the fcc lattices of the diamond structure.
Stretched SiC structures arise, which are coherently aligned to the Si matrix.
\si{} is believed to likewise compensate the tensile strain within these structures.
-This is followed by the precipitation into incoherent 3C-SiC once the strain energy of the coherent structure surpasses the interfacial energy of the incoherent precipitate and the c-Si substrate.
+This is followed by precipitation into incoherent 3C-SiC once the strain energy of the coherent structure surpasses the interfacial energy of the incoherent precipitate and the c-Si substrate.
The associated volume reduction is compensated by \si{} that may serve as a supply for further SiC or as a building block for the surrounding Si host and likewise reduce existing strain in the interface region.
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Results of the atomistic simulation study that indicate the respective precipitation mechanism conform well with other experimental findings.
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