\end{itemize}
$\Rightarrow$ mobile {\color{red}\ci} opposed to
stable {\color{blue}\cs{}} configurations
-\item Strained silicon \& Si$_{1-y}$C$_y$ heterostructures
+\item Strained Si$_{1-y}$C$_y$/Si heterostructures
{\tiny\color{gray}/Strane~et~al./Guedj~et~al./}
\begin{itemize}
- \item Initial {\color{blue}coherent} SiC precipitates (tensile strain)
+ \item Initial {\color{blue}coherent} SiC structures (tensile strain)
\item Incoherent SiC (strain relaxation)
\end{itemize}
\end{itemize}
\begin{itemize}
\item Bond-centered configuration unstable\\
$\rightarrow$ \ci{} \hkl<1 1 0> dumbbell
- \item Minima of the \hkl[0 0 -1] to \hkl[0 -1 0] transition\\
+ \item Minimum of the \hkl[0 0 -1] to \hkl[0 -1 0] transition\\
$\rightarrow$ \ci{} \hkl<1 1 0> DB
\end{itemize}
\vspace{0.1cm}
\begin{minipage}{6.1cm}
\scriptsize
\underline{Low C concentration --- {\color{red}$V_1$}}\\[0.1cm]
-\hkl<1 0 0> C-Si dumbbell dominated structure
+\ci{} \hkl<1 0 0> dumbbell dominated structure
\begin{itemize}
\item Si-C bumbs around \unit[0.19]{nm}
\item C-C peak at \unit[0.31]{nm} (expected in 3C-SiC):\\
\begin{minipage}{6cm}
\centering
Formation of \ci{} dumbbells\\
-C atoms in proper 3C-SiC distance first
+C atoms separated as expected in 3C-SiC
\end{minipage}
}}
\end{pspicture}\\[0.1cm]
\begin{minipage}{6.1cm}
\scriptsize
\underline{Low C concentration --- {\color{red}$V_1$}}\\[0.1cm]
-\hkl<1 0 0> C-Si dumbbell dominated structure
+\ci{} \hkl<1 0 0> dumbbell dominated structure
\begin{itemize}
\item Si-C bumbs around \unit[0.19]{nm}
\item C-C peak at \unit[0.31]{nm} (expected in 3C-SiC):\\
\vspace{0.2cm}
{\bf Time scale problem of MD}\\[0.2cm]
-Precise integration \& thermodynamic sampling\\
+Minimize integration error \& precise thermodynamic sampling\\
$\Rightarrow$ $\Delta t \ll \left( \max{\omega} \right)^{-1}$,
$\omega$: vibrational mode\\
$\Rightarrow$ {\color{red}\underline{Slow}} phase space propagation\\[0.2cm]
{\bf Limitations related to the short range potential}\\[0.2cm]
Cut-off function limits interaction to next neighbours\\
-$\Rightarrow$ Overestimated unphysical high forces of next neighbours
- (factor: 2.4--3.4)
+$\Rightarrow$ Overestimated diffusion barrier (factor: 2.4--3.4)
\vspace{1.4cm}
\underline{Si-C bonds:}
\begin{itemize}
\item Vanishing cut-off artifact (above $1650\,^{\circ}\mathrm{C}$)
- \item Structural change: C-Si \hkl<1 0 0> $\rightarrow$ C$_{\text{sub}}$
+ \item Structural change: \ci{} \hkl<1 0 0> DB $\rightarrow$
+ {\color{blue}\cs{}}
\end{itemize}
\underline{Si-Si bonds:}
{\color{blue}Si-C$_{\text{sub}}$-Si} along \hkl<1 1 0>
\underline{C-C bonds:}
\begin{itemize}
\item C-C next neighbour pairs reduced (mandatory)
- \item Peak at 0.3 nm slightly shifted
- \begin{itemize}
- \item C-Si \hkl<1 0 0> combinations (dashed arrows)\\
- $\rightarrow$ C-Si \hkl<1 0 0> \& C$_{\text{sub}}$
- combinations (|)\\
- $\rightarrow$ pure {\color{blue}C$_{\text{sub}}$ combinations}
- ($\downarrow$)
- \item Range [|-$\downarrow$]:
- {\color{blue}C$_{\text{sub}}$ \& C$_{\text{sub}}$
- with nearby Si$_{\text{I}}$}
- \end{itemize}
+ \item Peak at 0.3 nm slightly shifted\\[0.05cm]
+ $\searrow$ \ci{} combinations (dashed arrows)\\
+ $\nearrow$ \ci{} \hkl<1 0 0> \& {\color{blue}\cs{} combinations} (|)\\
+ $\nearrow$ \ci{} \hkl<1 0 0> \& \cs{} combinations (|)\\[0.05cm]
+ Range [|-$\downarrow$]: {\color{blue}\cs{} \& \cs{} with nearby \si}
\end{itemize}
\end{minipage}
\begin{itemize}
\item C-C next neighbour pairs reduced (mandatory)
\item Peak at 0.3 nm slightly shifted
- \begin{itemize}
- \item C-Si \hkl<1 0 0> combinations (dashed arrows)\\
- $\rightarrow$ C-Si \hkl<1 0 0> \& C$_{\text{sub}}$
- combinations (|)\\
- $\rightarrow$ pure {\color{blue}C$_{\text{sub}}$ combinations}
- ($\downarrow$)
- \item Range [|-$\downarrow$]:
- {\color{blue}C$_{\text{sub}}$ \& C$_{\text{sub}}$
- with nearby Si$_{\text{I}}$}
- \end{itemize}
+ \item Peak at 0.3 nm slightly shifted\\[0.05cm]
+ $\searrow$ \ci{} combinations (dashed arrows)\\
+ $\nearrow$ \ci{} \hkl<1 0 0> \& {\color{blue}\cs{} combinations} (|)\\
+ $\nearrow$ \ci{} \hkl<1 0 0> \& \cs{} combinations (|)\\[0.05cm]
+ Range [|-$\downarrow$]: {\color{blue}\cs{} \& \cs{} with nearby \si}
\end{itemize}
\end{minipage}
\item Low T $\rightarrow$ C-Si \hkl<1 0 0> dumbbell dominated structure
\item High T $\rightarrow$ C$_{\text{sub}}$ dominated structure
\item High T necessary to simulate IBS conditions (far from equilibrium)
- \item Increased participation of \cs{} in the precipitation process
+ \item \cs{} involved in the precipitation process at elevated temperatures
\item \si{}: vehicle to form \cs{} \& supply of Si \& stress compensation
(stretched SiC, interface)
\end{itemize}
\begin{center}
{\color{blue}\bf
-\framebox{Precipitation by successive agglomeration of \cs{}}
+\framebox{IBS: 3C-SiC precipitation occurs by successive agglomeration of \cs{}}
}
\end{center}