X-Git-Url: https://hackdaworld.org/gitweb/?p=lectures%2Flatex.git;a=blobdiff_plain;f=posic%2Fthesis%2Fsic.tex;h=7951724dbb02c10cd311045f632b926f09f89fd2;hp=d625900ebde3795c6ddcee3f8591682fc4d9c4d9;hb=0bcb803ceeceac852352af7809e2c88fa3d50860;hpb=4467ed9809f91a6b90790582f53c38466850be3b diff --git a/posic/thesis/sic.tex b/posic/thesis/sic.tex index d625900..7951724 100644 --- a/posic/thesis/sic.tex +++ b/posic/thesis/sic.tex @@ -107,7 +107,7 @@ Thus the cubic phase is most effective for highly efficient high-performance ele \label{fig:sic:unit_cell} \end{figure} Its unit cell is shown in Fig.~\ref{fig:sic:unit_cell}. -3C-SiC grows in zincblende structure, i.e. it is composed of two fcc lattices, which are displaced by one quarter of the volume diagonal as in Si. +3C-SiC grows in zincblende structure, i.e. it is composed of two face-centered cubic (fcc) lattices, which are displaced by one quarter of the volume diagonal as in Si. However, in 3C-SiC, one of the fcc lattices is occupied by Si atoms while the other one is occupied by C atoms. Its lattice constant of \unit[0.436]{nm} compared to \unit[0.543]{nm} from that of Si results in a lattice mismatch of almost \unit[20]{\%}, i.e. four lattice constants of Si approximately match five SiC lattice constants. Thus, the Si density of SiC is only slightly lower, i.e. \unit[97]{\%} of plain Si. @@ -410,7 +410,7 @@ Coherency is lost once the increasing strain energy of the stretched SiC structu Estimates of the SiC/Si interfacial energy \cite{taylor93} and the consequent critical size correspond well with the experimentally observed precipitate radii within these studies. This different mechanism 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. +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 substitutional C, which replaces four of the eight Si atoms in the Si unit cell accompanied by the generation of four Si interstitials. Since the emerging strain due to the expected volume reduction of \unit[48]{\%} would result in the formation of dislocations, which, however, are not observed, the interstitial Si is assumed to react with further implanted C atoms in the released volume. The resulting strain due to the slightly lower Si density of SiC compared to Si of about \unit[3]{\%} is sufficiently small to legitimate the absence of dislocations.