\chapter{Review of the silicon carbon compound}
+\label{chapter:sic_rev}
-\section{Properties and applications of silicon carbide}
+\section{Structure, properties and applications of silicon carbide}
-The stoichiometric composition of silicon and carbon termed silicon carbide (SiC) is the only chemical stable compound in the C/Si system \cite{}.
+The phase diagram of the C/Si system is shown in figure~\ref{fig:sic:si-c_phase}.
+The stoichiometric composition of silicon and carbon termed silicon carbide (SiC) is the only chemical stable compound in the C/Si system \cite{scace59}.
+\begin{figure}[ht]
+\begin{center}
+\includegraphics[width=12cm]{si-c_phase.eps}
+\end{center}
+\caption[Phase diagram of the C/Si system.]{Phase diagram of the C/Si system \cite{scace59}.}
+\label{fig:sic:si-c_phase}
+\end{figure}
SiC was first discovered by Henri Moissan in 1893 when he observed brilliant sparkling crystals while examining rock samples from a meteor crater in Arizona.
He mistakenly identified these crystals as diamond.
Although they might have been considered \glqq diamonds from space\grqq{} Moissan identified them as SiC in 1904 \cite{moissan04}.
In mineralogy SiC is still referred to as moissanite in honor of its discoverer.
It is extremely rare and almost impossible to find in nature.
-\subsection{SiC polytypes}
-
Each of the four sp$^3$ hybridized orbitals of the Si atom overlaps with one of the four sp$^3$ hybridized orbitals of the four surrounding C atoms and vice versa.
This results in fourfold coordinated covalent $\sigma$ bonds of equal length and strength for each atom with its neighbours.
-
Although the local order of Si and C next neighbour atoms characterized by the tetrahedral bonding is the same, more than 250 different types of structures called polytypes of SiC exist \cite{fischer90}.
-The polytypes differ in the one-dimensional stacking sequence of identical, closed-packed SiC bilayers.
+The polytypes differ in the one-dimensional stacking sequence of identical, close-packed SiC bilayers.
+\begin{figure}[ht]
+\begin{center}
+\includegraphics[width=12cm]{polytypes.eps}
+\end{center}
+\caption{Stacking sequence of SiC bilayers of the most common polytypes of SiC (from left to right): 3C, 2H, 4H and 6H.}
+\label{fig:sic:polytypes}
+\end{figure}
+Figure~\ref{fig:sic:polytypes} shows the stacking sequence of the most common and technologically most important SiC polytypes, which are the cubic (3C) and hexagonal (2H, 4H and 6H) polytypes.
+
+\begin{table}[ht]
+\begin{center}
+\begin{tabular}{l c c c c c c}
+\hline
+\hline
+ & 3C-SiC & 4H-SiC & 6H-SiC & Si & GaN & Diamond\\
+\hline
+Hardness [Mohs] & \multicolumn{3}{c}{------ 9.6 ------}& 6.5 & - & 10 \\
+Band gap [eV] & 2.36 & 3.23 & 3.03 & 1.12 & 3.39 & 5.5 \\
+Break down field$^{\text{A}}$ [$10^6$ V/cm] & 4 & 3 & 3.2 & 0.6 & 5 & 10 \\
+Saturation drift velocity$^{\text{A}}$ [$10^7$ cm/s] & 2.5 & 2.0 & 2.0 & 1 & 2.7 & 2.7 \\
+Electron mobility$^{\text{B}}$ [cm$^2$/Vs] & 800 & 900 & 400 & 1100 & 900 & 2200 \\
+Hole mobility$^{\text{B}}$ [cm$^2$/Vs] & 320 & 120 & 90 & 420 & 150 & 1600 \\
+Thermal conductivity [W/cmK] & 5.0 & 4.9 & 4.9 & 1.5 & 1.3 & 22 \\
+\hline
+\hline
+\end{tabular}
+\end{center}
+\caption[Properties of SiC polytypes and other semiconductor materials.]{Properties of SiC polytypes and other semiconductor materials. Doping concentrations are $10^{16}\text{ cm}^{-3}$ (A) and $10^{17}\text{ cm}^{-3}$ (B) respectively. References: \cite{wesch96,casady96}. {\color{red}Todo: add more refs + check all values!}}
+\label{table:sic:properties}
+\end{table}
+Different polytypes of SiC exhibit different properties.
+Some of the key properties are listed in table~\ref{table:sic:properties} and compared to other technologically relevant semiconductor materials.
+Despite the low carrier mobilities for low electric fields SiC outperforms Si concerning all other properties.
+The wide band gap ... light emitting diodes ... first blue led ... but GaN direct band gap semiconductor ...
+However ... combine all electr properties ... high-* .. .devices diodes, inverters ...
+break down field and high thermal conductivity ... high-densea and high-power ...
+high saturation drift velocity high-frequency ...
+Mechanical stability almost like diamond ...
+Chemical inert, low neutron capture foobar ... radiation hardness
+
+Since in this work 3C-SiC unit cell ... two fcc lattices ...
+
\section{Fabrication of silicon carbide}
\section{Ion beam synthesis of cubic silicon carbide}
+\section{Substoichiometric concentrations of carbon in crystalline silicon}
+
\section{Assumed precipitation mechanism of cubic silicon carbide in silicon}
\label{section:assumed_prec}
-\section{Substoichiometric concentrations of carbon in crystalline silicon}
-
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