\begin{document}
+\hyphenation{pho-to-lu-mi-nescence}
+
% Fliessenden Hintergrund von RGB-Farbe 1. .98 .98 nach 1. .85 .85
% und wieder nach 1. .98 .98 (1. .85 .85 wird nach 0.1=10% des Hinter-
% grunds angenommen)
\renewcommand{\columnfrac}{.31}
% header
-\vspace{-1cm}
+\vspace{-1.5cm}
\begin{header}
\begin{minipage} {.13\textwidth}
\includegraphics[height=11cm]{uni-logo.eps}
\begin{poster}
-\vspace{-1cm}
+\vspace{-1.1cm}
\begin{pcolumn}
\begin{pbox}
\section*{Motivation}
Experimentally observerd seflorganisation process at high-dose carbon
implantations under certain implantation conditions.}
\begin{itemize}
- \item Spherical and lamellar amorphous inclusions at the upper
- a/c interface
+ \item Regularly spaced, nanometric spherical and lamellar
+ amorphous inclusions at the upper a/c interface
\begin{center}
\includegraphics[width=20cm]{k393abild1_e.eps}
\end{center}
- Cross section TEM image:\\
+ Cross-section TEM bright-field image:\\
$180 \, keV$ $C^+ \rightarrow Si$,
- $T=150 \, ^{\circ} \mathrm{C}$,
+ $T_i=150 \, ^{\circ} \mathrm{C}$,
Dose: $4.3 \times 10^{17} \, cm^{-2}$\\
- black/white: crystalline/amorphous material\\
+ Amorphous inclusions appear white on darker backgrounds\\
L: amorphous lamellae, S: spherical amorphous inclusions
\item Carbon accumulation in amorphous volumes
\begin{center}
\includegraphics[width=20cm]{eftem.eps}
\end{center}
- Brightfield TEM and respective EFTEM image:\\
+ Bright-field TEM image and respective EFTEM $C$ map:\\
$180 \, keV$ $C^+ \rightarrow Si$,
- $T=200 \, ^{\circ} \mathrm{C}$,
+ $T_i=200 \, ^{\circ} \mathrm{C}$,
Dose: $4.3 \times 10^{17} \, cm^{-2}$\\
yellow/blue: high/low concentrations of carbon
\end{itemize}
{\bf
- Observed for a number of ion/target combinations for which the
+ Similarly ordered precipitate nanostructures also
+ observed for a number of ion/target combinations for which the
material undergoes drastic density change upon amorphisation.}\\
{\scriptsize
A. H. van Ommen, Nucl. Instr. and Meth. B 39 (1989) 194.\\
E. D. Specht et al., Nucl. Instr. and Meth. B 84 (1994) 323.\\
M. Ishimaru et al., Nucl. Instr. and Meth. B 166-167 (2000) 390.}
\end{pbox}
- \vspace{-1cm}
+ \vspace{-1.5cm}
\begin{pbox}
\section*{Model}
{\bf
\includegraphics[width=20cm]{modell_ng_e.eps}
\end{center}
\begin{itemize}
-\item supersaturation of $C$ in $c-Si$\\
- $\rightarrow$ {\bf carbon induced} nucleation of spherical
+\item Supersaturation of $C$ in $c-Si$\\
+ $\rightarrow$ {\bf Carbon induced} nucleation of spherical
$SiC_x$-precipitates
-\item high interfacial energy between $3C-SiC$ and $c-Si$\\
- $\rightarrow$ {\bf amourphous} precipitates
+\item High interfacial energy between $3C-SiC$ and $c-Si$\\
+ $\rightarrow$ {\bf Amourphous} precipitates
\item $20 - 30\,\%$ lower silicon density of $a-SiC_x$ compared to $c-Si$\\
- $\rightarrow$ {\bf lateral strain} (black arrows)
-\item implantation range near surface\\
- $\rightarrow$ {\bf ralaxation} of {\bf vertical strain component}
-\item reduction of the carbon supersaturation in $c-Si$\\
- $\rightarrow$ {\bf carbon diffusion} into amorphous volumina
+ $\rightarrow$ {\bf Lateral strain} (black arrows)
+\item Implantation range near surface\\
+ $\rightarrow$ {\bf Ralaxation} of {\bf vertical strain component}
+\item Reduction of the carbon supersaturation in $c-Si$\\
+ $\rightarrow$ {\bf Carbon diffusion} into amorphous volumina
(white arrows)
-\item remaining lateral strain\\
- $\rightarrow$ {\bf strain induced} lateral amorphisation
+\item Remaining lateral strain\\
+ $\rightarrow$ {\bf Strain enhanced} lateral amorphisation
+\item Absence of crystalline neighbours (structural information)\\
+ $\rightarrow$ {\bf Stabilisation} of amorphous inclusions
+ {\bf against recrystallisation}
\end{itemize}
\end{pbox}
- \vspace{-1cm}
+ \vspace{-1.5cm}
\begin{pbox}
\section*{Simulation}
\begin{minipage}[t]{0.5\textwidth}
\section*{Simulation algorithm}
{\bf
The simulation algorithm consists of the following three parts looped
- $s$ times corresponding to a dose $D=s/(64\times64\times(3 \, nm)^2)$:}
+ $s$ times corresponding to a dose
+ $D=s/(64\times64\times(3 \, nm)^2)$:}
\subsection*{1. Amorphisation/Recrystallisation}
\begin{itemize}
\item random numbers distributed according to
\end{itemize}
\subsection*{3. Diffusion/Sputtering}
\begin{itemize}
- \item every $d_v$ steps transfer $d_r$ of the
- carbon atoms of crystalline volumina to
+ \item every $d_v$ steps transfer of a fraction $d_r$
+ of carbon atoms from crystalline volumina to
an amorphous neighbour volume
- \item do the sputter routine after $n$ steps
- corresponding to $3 \, nm$ of substrat
- removal
+ \item remove $3 \, nm$ surface layer after $n$ loops,
+ shift remaining cells $3 \, nm$ up and insert
+ an empty, crystalline $3 \, nm$ bottom layer
\end{itemize}
+ \begin{picture}(0,0)(+40,-32)
+ \includegraphics[height=39.2cm]{loop-arrow.eps}
+ \end{picture}%
{\bf
Simulation parameters $d_v$, $d_r$ and $n$ control the
diffusion and sputtering process.}
\end{pbox}
- \vspace{-1cm}
+ \vspace{-0.27cm}
\begin{pbox}
\section*{Comparison of experiment and simulation}
\begin{center}
\includegraphics[width=25cm]{dosis_entwicklung_ng_e_2-2.eps}
\end{center}
Simulation parameters:\\
- $p_b=0.01$, $p_c=0.001$, $p_s=0.0001$, $d_r=0.05$, $d_v=1 \times 10^6$.
+ $p_b=0.01$, $p_c=0.001 \times (3 \, nm)^3$,
+ $p_s=0.0001 \times (3 \, nm)^5$, $d_r=0.05$, $d_v=1 \times 10^6$.
\\[0.7cm]{\bf Conclusion:}
\begin{itemize}
- \item Essentially conforming formation and growth of the
- continuous amorphous layer
+ \item Simulation in good agreement with experimentally observed
+ formation and growth of the continuous amorphous layer
\item Lamellar precipitates and their evolution at the upper
a/c interface with increasing dose is reproduced
\end{itemize}
implantation conditions between $8$ and
$10 \, at. \%$
\end{itemize}
- \end{minipage}
+ \end{minipage}%
\begin{minipage}[t]{0.43\textwidth}
\includegraphics[height=15cm]{97_98_ng_e.eps}
+ %\includegraphics[height=13cm]{gitter_e.eps}
+ %\includegraphics[height=15cm=]{test_foo.eps}
\begin{itemize}
\item Complementarily arranged and alternating sequence
of layers with high and low amount of amorphous
\end{itemize}
\end{minipage}
\end{pbox}
- \vspace{-1cm}
+ \vspace{-1.5cm}
\begin{pbox}
- \section*{Recipe:\\
- Thick films of ordered lamellar structure}
+ \section*{Recipe for thick films of ordered lamellae}
\begin{minipage}{0.33\textwidth}
{\bf Prerequisites:}\\
Crystalline silicon target with a nearly constant carbon
\end{minipage}
{\bf Creation:}
\begin{itemize}
- \item multiple energy ($180$-$10 \, keV$) $C^+$ $\rightarrow$
+ \item Multiple energy ($180$-$10 \, keV$) $C^+$ $\rightarrow$
$Si$ implantation
- \item $T=500 \, ^{\circ} \mathrm{C}$, to prevent amorphisation
+ \item $T_i=500 \, ^{\circ} \mathrm{C}$, to prevent amorphisation
\end{itemize}
\vspace{1cm}
- {\bf Stiring up:}\\[0.5cm]
- 2nd $2 \, MeV$ $C^+$ $\rightarrow$ $Si$ implantation step at
+ {\bf Stirring up:}\\[0.5cm]
+ $2 \, MeV$ $C^+$ $\rightarrow$ $Si$ irradiation step at
$150 \, ^{\circ} \mathrm{C}$
\begin{itemize}
\item This does not significantly change the carbon
concentration in the top $500 \, nm$
- \item Nearly constant energy loss in the affected depth region
+ \item Nearly constant nuclear energy loss in the top $700 \, nm$
+ region
\end{itemize}
\vspace{1cm}
{\bf Result:}
\vspace{0.7cm}
\begin{center}
- \includegraphics[width=25cm]{multiple_impl_e.eps}
+ \includegraphics[width=25cm]{multiple_impl_e_ver2.eps}
\end{center}
\begin{itemize}
\item Already ordered structures after $100 \times 10^6$ steps
corresponding to a dose of $D=2.7 \times 10^{17} cm^{-2}$
\item More defined structures with increasing dose
\end{itemize}
- {\bf\color{blue} Starting point for materials showing strong\\
+ {\bf\color{blue} Starting point for materials showing strong
photoluminescence}\\
{\scriptsize Dihu Chen et al. Opt. Mater. 23 (2003) 65.}
\end{pbox}
- \vspace{-1cm}
+ \vspace{-1.5cm}
\begin{pbox}
\section*{Conclusions}
\begin{itemize}
- \item Observation of self-organised nanometric
+ \item Observation of selforganised nanometric
precipitates by ion irradiation
- \item Model proposed describing the seoforganisation
+ \item Model proposed describing the selforganisation
process
- \item Model implemented to a Monte Carlo simulation code
- \item Simulation is able to reproduce experimental
- observations
+ \item Model implemented in a Monte Carlo simulation code
\item Modelling of the complete depth region affected
by the irradiation process
+ \item Simulation is able to reproduce entire amorphous
+ phase formation
\item Precipitation process gets traceable by simulation
\item Detailed structural/compositional information
available by simulation
- \item Recipe proposed for the formation of broad
- distributions of lamellar structure
+ \item Recipe proposed for the formation of thick films
+ of lamellar structure
\end{itemize}
\end{pbox}
+ \vspace{-1.5cm}
+ \begin{pbox}
+ \section*{Publications}
+ {\scriptsize
+ F. Zirkelbach, M. H"aberlen, J. K. N. Lindner,
+ B. Stritzker. Comp. Mater. Sci. 33 (2005) 310.\\
+ F. Zirkelbach, M. H"aberlen, J. K. N. Lindner,
+ B. Stritzker. Nucl. Instr. and Meth. B 242 (2006) 679.}
+ \end{pbox}
\end{pcolumn}
\end{poster}
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