X-Git-Url: https://hackdaworld.org/gitweb/?p=lectures%2Flatex.git;a=blobdiff_plain;f=posic%2Fthesis%2Fsic.tex;h=5629f6f132be09ca6e1501b665b4e3346702dc59;hp=0379687e3eab31da63bc58ad8aa752a43daaf38b;hb=7aaa88055445022d118d09860dc3412871c9eb9c;hpb=cf625066e6ada2a8d680e2a77bb2f5c6eb5122ab

diff --git a/posic/thesis/sic.tex b/posic/thesis/sic.tex
index 0379687..5629f6f 100644
--- a/posic/thesis/sic.tex
+++ b/posic/thesis/sic.tex
@@ -26,13 +26,21 @@ The polytypes differ in the one-dimensional stacking sequence of identical, clos
 Each SiC bilayer can be situated in one of three possible positions (abbreviated a, b or c) with respect to the lattice while maintaining the tetrahedral bonding scheme of the crystal.
 \begin{figure}[t]
 \begin{center}
-\includegraphics[width=10cm]{polytypes.eps}
+\includegraphics[height=5.5cm]{polytypes_own.eps}\\[0.1cm]
+\begin{minipage}{0.45\textwidth}
+{\small
+\hspace*{0.05cm} a \hspace*{0.09cm} b \hspace*{0.09cm} c \hspace*{0.44cm} a \hspace*{0.09cm} b \hspace*{0.44cm} a \hspace*{0.09cm} b \hspace*{0.09cm} c \hspace*{0.44cm} a \hspace*{0.09cm} b \hspace*{0.09cm} c \hspace*{0.09cm} a\\
+\hspace*{0.5cm} 3C \hspace*{0.9cm} 2H \hspace*{1.0cm} 4H \hspace*{1.3cm} 6H
+}
+\end{minipage}
+%\includegraphics[width=10cm]{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}
 Fig.~\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.
 
+\bibpunct{}{}{,}{n}{}{}
 \begin{table}[t]
 \begin{center}
 \begin{tabular}{l c c c c c c}
@@ -51,9 +59,11 @@ Thermal conductivity [W/cmK] & 5.0 & 4.9 & 4.9 & 1.5 & 1.3 & 22 \\
 \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,park98}. {\color{red}Todo: add more refs + check all values!}}
+\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,park98}.}
 \label{table:sic:properties}
 \end{table}
+\bibpunct{[}{]}{,}{n}{}{}
+% todo add more refs + check all values!
 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 lower charge carrier mobilities for low electric fields SiC outperforms Si concerning all other properties.
@@ -342,7 +352,7 @@ However, there is great interest to incorporate C onto substitutional lattice si
 Thus, substitutional C enables strain engineering of Si and Si/Si$_{1-x}$Ge$_x$ heterostructures \cite{yagi02,chang05,kissinger94,osten97}, which is used to increase charge carrier mobilities in Si as well as to adjust its band structure \cite{soref91,kasper91}.
 % increase of C at substitutional sites
 Epitaxial layers with \unit[1.4]{at.\%} of substitutional C have been successfully synthesized in preamorphized Si$_{0.86}$Ge$_{0.14}$ layers, which were grown by CVD on Si substrates, using multiple-energy C implantation followed by solid-physe epitaxial regrowth at \unit[700]{$^{\circ}$C} \cite{strane93}.
-The tensile strain induced by the C atoms is found to compensates the compressive strain present due to the Ge atoms.
+The tensile strain induced by the C atoms is found to compensate the compressive strain present due to the Ge atoms.
 Studies on the thermal stability of Si$_{1-y}$C$_y$/Si heterostructures formed in the same way and equal C concentrations showed a loss of substitutional C accompanied by strain relaxation for temperatures ranging from \unit[810-925]{$^{\circ}$C} and the formation of spherical 3C-SiC precipitates with diameters of \unit[2-4]{nm}, which are incoherent but aligned to the Si host \cite{strane94}.
 During the initial stages of precipitation C-rich clusters are assumed, which maintain coherency with the Si matrix and the associated biaxial strain.
 Using this technique a metastable solubility limit was achieved, which corresponds to a C concentration exceeding the solid solubility limit at the Si melting point by nearly three orders of magnitude and, furthermore, a reduction of the defect denisty near the metastable solubility limit is assumed if the regrowth temperature is increased by rapid thermal annealing \cite{strane96}.
@@ -359,7 +369,7 @@ Indeed, closely investigating the large amount of literature pulled up in the la
 High resolution transmission electron microscopy (HREM) investigations of C-implanted Si at room temperature followed by rapid thermal annealing (RTA) show the formation of C-Si dumbbell agglomerates, which are stable up to annealing temperatures of about \unit[700-800]{$^{\circ}$C}, and a transformation into 3C-SiC precipitates at higher temperatures \cite{werner96,werner97}.
 The precipitates with diamateres between \unit[2]{nm} and \unit[5]{nm} are incorporated in the Si matrix without any remarkable strain fields, which is explained by the nearly equal atomic density of C-Si agglomerates and the SiC unit cell.
 Implantations at \unit[500]{$^{\circ}$C} likewise suggest an initial formation of C-Si dumbbells on regular Si lattice sites, which agglomerate into large clusters \cite{lindner99_2}.
-The agglomerates of such dimers, which do not generate lattice strain but lead to a local increase of the lattice potential \cite{werner96}, are indicated by dark contrasts and otherwise undisturbed Si lattice fringes in HREM, as can be seen in Fig.~\ref{fig:sic:hrem:c-si}.
+The agglomerates of such dimers, which do not generate lattice strain but lead to a local increase of the lattice potential \cite{werner96,werner97}, are indicated by dark contrasts and otherwise undisturbed Si lattice fringes in HREM, as can be seen in Fig.~\ref{fig:sic:hrem:c-si}.
 \begin{figure}[t]
 \begin{center}
 \subfigure[]{\label{fig:sic:hrem:c-si}\includegraphics[width=0.25\columnwidth]{tem_c-si-db.eps}}
@@ -418,7 +428,5 @@ On the other hand, processes relying upon prevention of precipitation in order t
 % eichhorn02: high imp temp more efficient than postimp treatment
 % eichhorn99: same as 02 + c-si agglomerates at low concentrations
 % strane94/guedj98: my model - c redist by si int (spe) and surface diff (mbe)
-
-% todo
-% own polytype stacking sequence image
+% serre95: low/high t implants -> mobile c_i / non-mobile sic precipitates