\usepackage{pstricks}
\usepackage{pst-node}
+\usepackage{pst-grad}
%\usepackage{epic}
%\usepackage{eepic}
\end{center}
\end{slide}
+% no vertical centering
+\centerslidesfalse
+
\ifnum1=0
% intro
\begin{slide}
+\vspace*{1.8cm}
+
\small
\begin{pspicture}(0,0)(13.5,5)
\end{slide}
-\fi
% fabrication
\begin{slide}
\vspace{2pt}
+\begin{center}
{\color{gray}
\emph{Silicon carbide --- Born from the stars, perfected on earth.}
}
+\end{center}
\vspace{2pt}
-SiC thin film by MBE \& CVD
+SiC thin films by MBE \& CVD
\begin{itemize}
\item Much progress achieved in homo/heteroepitaxial SiC thin film growth
\item \underline{Commercially available} semiconductor power devices based on
\includegraphics[width=2.0cm]{cree.eps}
\end{picture}
-Alternative method: Ion beam synthesis of SiC in Si
+\vspace{-0.2cm}
- \begin{itemize}
- \item \underline{Sublimation growth using the modified Lely method}
- \begin{itemize}
- \item SiC single-crystalline seed at $T=1800 \, ^{\circ} \text{C}$
- \item Surrounded by polycrystalline SiC in a graphite crucible\\
- at $T=2100-2400 \, ^{\circ} \text{C}$
- \item Deposition of supersaturated vapor on cooler seed crystal
- \end{itemize}
- \item \underline{Homoepitaxial growth using CVD}
- \begin{itemize}
- \item Step-controlled epitaxy on off-oriented 6H-SiC substrates
- \item C$_3$H$_8$/SiH$_4$/H$_2$ at $1100-1500 \, ^{\circ} \text{C}$
- \item Angle, temperature $\rightarrow$ 3C/6H/4H-SiC
- \end{itemize}
- \item \underline{Heteroepitaxial growth of 3C-SiC on Si using CVD/MBE}
- \begin{itemize}
- \item Two steps: carbonization and growth
- \item $T=650-1050 \, ^{\circ} \text{C}$
- \item SiC/Si lattice mismatch $\approx$ 20 \%
- \item Quality and size not yet sufficient
- \end{itemize}
- \end{itemize}
+Alternative approach:
+Ion beam synthesis (IBS) of burried 3C-SiC layers in Si\hkl(1 0 0)
- \begin{picture}(0,0)(-280,-65)
- \includegraphics[width=3.8cm]{6h-sic_3c-sic.eps}
- \end{picture}
- \begin{picture}(0,0)(-280,-55)
- \begin{minipage}{5cm}
- {\tiny
- NASA: 6H-SiC and 3C-SiC LED\\[-7pt]
- on 6H-SiC substrate
- }
- \end{minipage}
- \end{picture}
- \begin{picture}(0,0)(-265,-150)
- \includegraphics[width=2.4cm]{m_lely.eps}
- \end{picture}
- \begin{picture}(0,0)(-333,-175)
- \begin{minipage}{5cm}
- {\tiny
- 1. Lid\\[-7pt]
- 2. Heating\\[-7pt]
- 3. Source\\[-7pt]
- 4. Crucible\\[-7pt]
- 5. Insulation\\[-7pt]
- 6. Seed crystal
- }
- \end{minipage}
- \end{picture}
- \begin{picture}(0,0)(-230,-35)
- \framebox{
- {\footnotesize\color{blue}\bf Hex: micropipes along c-axis}
+\vspace{0.2cm}
+
+\scriptsize
+
+\framebox{
+\begin{minipage}{3.15cm}
+ \begin{center}
+\includegraphics[width=3cm]{imp.eps}\\
+ {\tiny
+ Carbon implantation
}
- \end{picture}
- \begin{picture}(0,0)(-230,-10)
- \framebox{
- \begin{minipage}{3cm}
- {\footnotesize\color{blue}\bf 3C-SiC fabrication\\
- less advanced}
- \end{minipage}
+ \end{center}
+\end{minipage}
+\begin{minipage}{3.15cm}
+ \begin{center}
+\includegraphics[width=3cm]{annealing.eps}\\
+ {\tiny
+ \unit[12]{h} annealing at \degc{1200}
}
- \end{picture}
+ \end{center}
+\end{minipage}
+}
+\begin{minipage}{5.5cm}
+ \includegraphics[width=5.8cm]{ibs_3c-sic.eps}\\[-0.2cm]
+ \begin{center}
+ {\tiny
+ XTEM: single crystalline 3C-SiC in Si\hkl(1 0 0)
+ }
+ \end{center}
+\end{minipage}
\end{slide}
-\end{document}
-\ifnum1=0
-
% contents
\begin{slide}
+{\large\bf
+ Systematic investigation of C implantations into Si
+}
+
+\vspace{1.7cm}
+\begin{center}
+\hspace{-1.0cm}
+\includegraphics[width=0.75\textwidth]{imp_inv.eps}
+\end{center}
+
+\end{slide}
+
+% outline
+
+\fi
+
+\begin{slide}
+
{\large\bf
Outline
}
- \begin{itemize}
- \item Implantation of C in Si --- Overview of experimental observations
- \item Utilized simulation techniques and modeled problems
- \begin{itemize}
- \item {\color{blue}Diploma thesis}\\
- \underline{Monte Carlo} simulations
- modeling the selforganization process
- leading to periodic arrays of nanometric amorphous SiC
- precipitates
- \item {\color{blue}Doctoral studies}\\
- Classical potential \underline{molecular dynamics} simulations
- \ldots\\
- \underline{Density functional theory} calculations
- \ldots\\[0.2cm]
- \ldots on defects and SiC precipitation in Si
- \end{itemize}
- \item Summary / Conclusion / Outlook
- \end{itemize}
+\vspace{1.7cm}
+\begin{center}
+\hspace{-1.0cm}
+\includegraphics[width=0.75\textwidth]{imp_inv.eps}
+\end{center}
+
+\begin{pspicture}(0,0)(0,0)
+\rput(6.0,7.0){\rnode{init}{\psframebox[fillstyle=gradient,gradbegin=white,gradend=red,gradlines=1000,gradmidpoint=0.5,linestyle=none]{
+\begin{minipage}{11cm}
+{\color{black}Diploma thesis}\\
+ \underline{Monte Carlo} simulation modeling the selforganization process\\
+ leading to periodic arrays of nanometric amorphous SiC precipitates
+\end{minipage}
+}}}
+\end{pspicture}
+\begin{pspicture}(0,0)(0,0)
+\rput(6.0,-0.5){\rnode{init}{\psframebox[fillstyle=gradient,gradbegin=white,gradend=blue,gradmidpoint=0.5,gradlines=1000,linestyle=none]{
+\begin{minipage}{11cm}
+{\color{black}Doctoral studies}\\
+ Classical potential \underline{molecular dynamics} simulations \ldots\\
+ \underline{Density functional theory} calculations \ldots\\[0.2cm]
+ \ldots on defect formation and SiC precipitation in Si
+\end{minipage}
+}}}
+\end{pspicture}
+\begin{pspicture}(0,0)(0,0)
+\psellipse[linecolor=red,linewidth=0.05cm](5,3.0)(0.8,1.0)
+\end{pspicture}
+\begin{pspicture}(0,0)(0,0)
+\psellipse[linecolor=blue,linewidth=0.05cm](8.2,3.2)(1.5,1.6)
+\end{pspicture}
\end{slide}
+\begin{slide}
+{\large\bf
+ Selforganization of nanometric amorphous SiC lamellae
+}
+
+\begin{pspicture}(0,0)(0,0)
+\psframebox[fillstyle=gradient,gradbegin=white,gradend=red,gradlines=1000,gradmidpoint=0.5,linestyle=none]{
+\begin{minipage}{14cm}
+\hfill
+\vspace*{0.5cm}
+\end{minipage}
+}
+\end{pspicture}
+
+\small
+
+\vspace{0.2cm}
+
+\begin{itemize}
+ \item Regularly spaced, nanometric spherical\\
+ and lamellar amorphous inclusions\\
+ at the upper a/c interface
+ \item Carbon accumulation\\
+ in amorphous volumes
+\end{itemize}
+
+\vspace{0.4cm}
+
+\begin{minipage}{12cm}
+\includegraphics[width=9cm]{../../nlsop/img/k393abild1_e_l.eps}\\
+{\scriptsize
+XTEM bright-field, \unit[180]{keV} C$^+ \rightarrow$ Si, \degc{150},
+Dose: \unit[4.3 $\times 10^{17}$]{cm$^{-2}$}
+}
+\end{minipage}
+
+\begin{picture}(0,0)(-182,-215)
+\begin{minipage}{6.5cm}
+\begin{center}
+\includegraphics[width=6.5cm]{../../nlsop/img/eftem.eps}\\[-0.2cm]
+{\scriptsize
+XTEM bright-field and respective EFTEM C map
+}
+\end{center}
+\end{minipage}
+\end{picture}
+
+\end{slide}
\end{document}
+\ifnum1=0
\begin{slide}
- {\large\bf
- Fabrication of silicon carbide
- }
+{\large\bf
+ Model displaying the formation of ordered lamellae
+}
- \small
+\vspace{0.1cm}
- Alternative approach:
- Ion beam synthesis (IBS) of burried 3C-SiC layers in Si\hkl(1 0 0)
- \begin{itemize}
- \item \underline{Implantation step 1}\\
- 180 keV C$^+$, $D=7.9\times 10^{17}$ cm$^{-2}$, $T_{\text{i}}=500\,^{\circ}\mathrm{C}$\\
- $\Rightarrow$ box-like distribution of equally sized
- and epitactically oriented SiC precipitates
-
- \item \underline{Implantation step 2}\\
- 180 keV C$^+$, $D=0.6\times 10^{17}$ cm$^{-2}$, $T_{\text{i}}=250\,^{\circ}\mathrm{C}$\\
- $\Rightarrow$ destruction of SiC nanocrystals
- in growing amorphous interface layers
- \item \underline{Annealing}\\
- $T=1250\,^{\circ}\mathrm{C}$, $t=10\,\text{h}$\\
- $\Rightarrow$ homogeneous, stoichiometric SiC layer
- with sharp interfaces
- \end{itemize}
+\begin{center}
+ \includegraphics[width=8.0cm]{../../nlsop/img/modell_ng_e.eps}
+\end{center}
+
+\footnotesize
+
+\begin{itemize}
+\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 Amorphous} precipitates
+\item \unit[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 Relaxation} 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 enhanced} lateral amorphisation
+\item Absence of crystalline neighbours (structural information)\\
+ $\rightarrow$ {\bf Stabilization} of amorphous inclusions
+ {\bf against recrystallization}
+\end{itemize}
+
+\end{slide}
+
+\begin{slide}
+
+{\large\bf
+ Implementation of the Monte Carlo code
+}
+
+\small
+
+\begin{enumerate}
+ \item \underline{Amorphization / Recrystallization}\\
+ Ion collision in discretized target determined by random numbers
+ distributed according to nuclear energy loss.
+ Amorphization/recrystallization probability:
+\[
+p_{c \rightarrow a}(\vec{r}) = {\color{green} p_b} + {\color{blue} p_c c_C(\vec{r})} + {\color{red} \sum_{\textrm{amorphous neighbours}} \frac{p_s c_C(\vec{r'})}{(r-r')^2}}
+\]
+\begin{itemize}
+ \item {\color{green} $p_b$} normal `ballistic' amorphization
+ \item {\color{blue} $p_c$} carbon induced amorphization
+ \item {\color{red} $p_s$} stress enhanced amorphization
+\end{itemize}
+\[
+p_{a \rightarrow c}(\vec r) = (1 - p_{c \rightarrow a}(\vec r)) \Big(1 - \frac{\sum_{direct \, neighbours} \delta (\vec{r'})}{6} \Big) \, \textrm{,}
+\]
+\[
+\delta (\vec r) = \left\{
+\begin{array}{ll}
+ 1 & \textrm{if volume at position $\vec r$ is amorphous} \\
+ 0 & \textrm{otherwise} \\
+\end{array}
+\right.
+\]
+ \item \underline{Carbon incorporation}\\
+ Incorporation volume determined according to implantation profile
+ \item \underline{Diffusion / Sputtering}
+ \begin{itemize}
+ \item Transfer fraction of C atoms
+ of crystalline into neighbored amorphous volumes
+ \item Remove surface layer
+ \end{itemize}
+\end{enumerate}
+
+\end{slide}
+
+\begin{slide}
+
+\begin{minipage}{3.7cm}
+{\large\bf
+ Results
+}
+
+\footnotesize
+
+\vspace{1.0cm}
+
+Evolution of the \ldots
+\begin{itemize}
+ \item continuous\\
+ amorphous layer
+ \item a/c interface
+ \item lamella precipitates
+\end{itemize}
+\ldots reproduced!\\[1.5cm]
+
+{\color{blue}
+\begin{center}
+Experiment \& simulation\\
+in good agreement\\[1.0cm]
+
+Simulation is able to model the whole depth region\\[1.0cm]
+\end{center}
+}
+
+\end{minipage}
+\begin{minipage}{0.4cm}
+\vfill
+\end{minipage}
+\begin{minipage}{8.0cm}
+ \vspace{-0.2cm}
+ \includegraphics[width=9cm]{../../nlsop/img/dosis_entwicklung_ng_e_1-2.eps}\\
+ \includegraphics[width=9cm]{../../nlsop/img/dosis_entwicklung_ng_e2_2-2.eps}
+\end{minipage}
+
+\end{slide}
+
+\begin{slide}
+
+{\large\bf
+ Structural \& compositional details
+}
+
+\begin{minipage}[t]{7.5cm}
+\includegraphics[height=6.5cm]{../../nlsop/img/ac_cconc_ver2_e.eps}\\
+\end{minipage}
+\begin{minipage}[t]{5.0cm}
+\includegraphics[height=6.5cm]{../../nlsop/img/97_98_e.eps}
+\end{minipage}
+
+\footnotesize
+
+\vspace{-0.1cm}
+
+\begin{itemize}
+ \item Fluctuation of C concentration in lamellae region
+ \item \unit[8--10]{at.\%} C saturation limit
+ within the respective conditions
+ \item Complementarily arranged and alternating sequence of layers\\
+ with a high and low amount of amorphous regions
+ \item C accumulation in the amorphous phase / Origin of stress
+\end{itemize}
+
+\begin{picture}(0,0)(-265,-30)
+\framebox{
+\begin{minipage}{3cm}
+\begin{center}
+{\color{blue}
+Precipitation process\\
+gets traceable\\
+by simulation!
+}
+\end{center}
+\end{minipage}
+}
+\end{picture}
+
+\end{slide}
+
+
+\end{document}
+
+% continue here
+\fi
+
+\ifnum1=0
+
+\begin{slide}
+
+{\large\bf
+ Model displaying the formation of ordered lamellae
+}
- \begin{minipage}{6.3cm}
- \includegraphics[width=6cm]{ibs_3c-sic.eps}\\[-0.2cm]
- {\tiny
- XTEM micrograph of single crystalline 3C-SiC in Si\hkl(1 0 0)
- }
- \end{minipage}
\framebox{
\begin{minipage}{6.3cm}
\begin{center}
\end{center}
\end{minipage}
}
-
-\end{slide}
+\end{slide}
\begin{slide}
projects / lectures / latex.git / blobdiff