-High-dose carbon implantation at elevated temperatures into silicon with subsequent annealing results in the formation of buried epitaxial SiC layers \cite{borders71,reeson87}.
-A two-temperature implantation technique was proposed to achieve single crytalline SiC layers and a sharp SiC/Si interface \cite{lindner99,lindner99_2,lindner01,lindner02}.
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-Although high-quality SiC can be achieved by means of IBS the precipitation mechanism is not yet fully understood.
-High resolution transmisson electron microscopy (HRTEM) 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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+High-dose carbon implantation at elevated temperatures into silicon with subsequent annealing results in the formation of buried SiC layers~\cite{borders71,reeson87}.
+A two-temperature implantation technique was proposed to achieve single crystalline, epitaxial SiC layers and a sharp SiC/Si interface~\cite{lindner99,lindner99_2,lindner01,lindner02}.
+
+Although high-quality SiC can be achieved by means of IBS, the precipitation mechanism is not yet fully understood.
+High resolution transmission 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}.
+In contrast, investigations of strained Si$_{1-y}$C$_y$/Si heterostructures formed 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~\cite{nejim95}, a topotactic transformation is proposed 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.
+The atomic migration involved in such a transformation is not clear.
+
+For several reasons, solving the controversial view of SiC precipitation in Si is of fundamental interest.