Although high-quality SiC can be achieved by means of IBS the precipitation mechanism is not yet fully understood.
High resolution transmisson electron microscopy studies indicate the formation of C-Si interstitial complexes sharing conventional silicon lattice sites (C-Si dumbbells) during the implantation of carbon in silicon.
These C-Si dumbbells agglomerate and once a critical radius is reached, the topotactic transformation into a SiC precipitate occurs \cite{werner97,lindner01}.
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+In contrast, investigations of strained Si$_{1-y}$C$_y$/Si heterostructures form
+ed by MBE~\cite{strane94,guedj98}, which incidentally involve the formation of SiC nanocrystallites, suggest an initial coherent precipitation by agglomeration of substitutional instead of interstitial C.
+Coherency is lost once the increasing strain energy of the stretched SiC structure surpasses the interfacial energy of the incoherent 3C-SiC precipitate and the Si substrate.
+These two different mechanisms of precipitation might be attributed to the respective method of fabrication.
+While in CVD and MBE surface effects need to be taken into account, SiC formation during IBS takes place in the bulk of the Si crystal.
+However, in another IBS study, Nejim et~al.~\cite{nejim95} propose a topotactic transformation that is likewise based on the formation of substitutional C, which is accompanied by the emission of Si self-interstitial atoms that previously occupied the lattice sites and a compensating reduction of volume due to the lower lattice constant of SiC compared to Si.
+
+For several reasons, solving the controversial view of SiC precipitation in Si is of fundamental interest.
A better understanding of the supposed SiC conversion mechanism and related carbon-mediated effects in silicon will enable significant technological progress in SiC thin film formation on the one hand and likewise offer perspectives for processes which rely upon prevention of precipitation events for improved silicon based devices on the other hand.
Implanted carbon is known to suppress transient enhanced diffusion of dopant species like boron or phosphorus in the annealing step \cite{cowern96} which can be exploited to create shallow p-n junctions in submicron technologies.
Si self-interstitials (Si$_{\text{i}}$), known as the transport vehicles for dopants \cite{fahey89,stolk95}, get trapped by reacting with the carbon atoms \cite{stolk97}.
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