started fabrication chapter

diff --git a/posic/thesis/sic.tex b/posic/thesis/sic.tex
index e9b44e4..c729f24 100644 (file)
--- a/posic/thesis/sic.tex
+++ b/posic/thesis/sic.tex
@@ -96,16 +96,42 @@ Thus the cubic phase is most effective for highly efficient high-performance ele
 \caption{3C-SiC unit cell. Yellow and grey spheres correpsond to Si and C atoms respectively. Covalent bonds are illustrated by blue lines.}
 \label{fig:sic:unit_cell}
 \end{figure}
-The 3C-SiC unit cell is shown in Fig.~\ref{fig:sic:unit_cell}.
+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.
 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 match five SiC lattice constants.
-Thus, the Si density of SiC is only slightly lower, i.e. \unit[97]{\%}, than that of Si.
+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.
 
 \section{Fabrication of silicon carbide}
 
-SiC usually manmade.
-The unique properties driving its applications in the same time harden the fabrication of SiC ...
+Although the constituents of SiC are abundant and the compound is chemically and thermally stable, large deposits of SiC have never been found.
+Due to the rarity, SiC is typically man-made.
+The development of several methods was necessary to synthetically produce SiC crystals matching the needs of a respective application.
+The fact that natural SiC is almost only observed as individual presolar SiC stardust grains near craters of primitive meteorite impacts, already indicates the complexity involved in the synthesis process.
+
+The attractive properties and wide range of applications, however, have triggered extensive efforts to grow this material as a bulk crystal and as an epitaxial surface thin film.
+In the following, the principal difficulties involved in the formation of crystalline SiC and the most recent achievements will be summarized.
+
+Though possible, melt growth processes \cite{nelson69} are complicated due to the small C solubility in Si at temperatures below \unit[2000]{$^{\circ}$C} and its small change with temperature \cite{scace59}.
+High process temperatures are necessary and the evaporation of Si must be suppressed by a high-pressure inert atmosphere.
+Crystals grown by this method are not adequate for practical applications with respect to their size as well as quality and purity.
+The presented methods, thus, focus on vapor transport growth processes such as chemical vapor deposition (CVD) or molecular beam epitaxy (MBE) and the sublimation technique.
+
+\subsection{SiC bulk crystal growth}
+
+The industrial Acheson process \cite{acheson} is utilized to produce SiC on a large scale by thermal reaction of silicon dioxide (silica sand) and carbon.
+Due to the insufficient and uncontrollable purity, material produced by this method, originally termed carborundum by Acheson, can hardly be used for device applications.
+However, it is often used as an abrasive material and as seed crystals for subsequent vapor phase growth and sublimation processes.
+
+van Arkel (CVD)
+
+Lely (sublimation)
+
+modified Lely or modified sublimation
+
+though significant advances have been achieved a bunch of defects ...
+
+\subsection{SiC epitaxial thin film growth}
 
 \section{Ion beam synthesis of cubic silicon carbide}