\usepackage{graphicx}
\graphicspath{{../img/}}
+\usepackage{miller}
+
\usepackage[setpagesize=false]{hyperref}
\usepackage{semcolor}
}
\begin{itemize}
- \item Fabrication of silicon carbide and different polytypes
- \item Precipitation model of 3C-SiC in Si
+ \item Polyteps and fabrication of silicon carbide
+ \item Supposed precipitation mechanism of SiC in Si
\item Utilized simulation techniques
\begin{itemize}
\item Molecular dynamics (MD) simulations
\item Density functional theory (DFT) calculations
\end{itemize}
\item C and Si self-interstitial point defects in silicon
- \item Precipitation simulations
+ \item Silicon carbide precipitation simulations
+ \item Investigation of a silicon carbide precipitate in silicon
\item Summary / Conclusion / Outlook
\end{itemize}
\end{slide}
+\begin{slide}
+
+ {\large\bf
+ Fabrication of silicon carbide
+ }
+
+ \small
+
+ 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{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}
+ \begin{minipage}{6.3cm}
+ \begin{center}
+ {\color{blue}
+ Precipitation mechanism not yet fully understood!
+ }
+ \renewcommand\labelitemi{$\Rightarrow$}
+ \small
+ \underline{Understanding the SiC precipitation}
+ \begin{itemize}
+ \item significant technological progress in SiC thin film formation
+ \item perspectives for processes relying upon prevention of SiC precipitation
+ \end{itemize}
+ \end{center}
+ \end{minipage}
+
+\end{slide}
+
+\begin{slide}
+
+ {\large\bf
+ Supposed precipitation mechanism of SiC in Si
+ }
+
+ \scriptsize
+
+ \vspace{0.1cm}
+
+ \begin{minipage}{3.8cm}
+ Si \& SiC lattice structure\\[0.2cm]
+ \includegraphics[width=3.5cm]{sic_unit_cell.eps}\\[-0.3cm]
+ \hrule
+ \end{minipage}
+ \hspace{0.6cm}
+ \begin{minipage}{3.8cm}
+ \begin{center}
+ \includegraphics[width=3.3cm]{tem_c-si-db.eps}
+ \end{center}
+ \end{minipage}
+ \hspace{0.6cm}
+ \begin{minipage}{3.8cm}
+ \begin{center}
+ \includegraphics[width=3.3cm]{tem_3c-sic.eps}
+ \end{center}
+ \end{minipage}
+
+ \begin{minipage}{4cm}
+ \begin{center}
+ C-Si dimers (dumbbells)\\[-0.1cm]
+ on Si interstitial sites
+ \end{center}
+ \end{minipage}
+ \hspace{0.2cm}
+ \begin{minipage}{4.2cm}
+ \begin{center}
+ Agglomeration of C-Si dumbbells\\[-0.1cm]
+ $\Rightarrow$ dark contrasts
+ \end{center}
+ \end{minipage}
+ \hspace{0.2cm}
+ \begin{minipage}{4cm}
+ \begin{center}
+ Precipitation of 3C-SiC in Si\\[-0.1cm]
+ $\Rightarrow$ Moir\'e fringes\\[-0.1cm]
+ \& release of Si self-interstitials
+ \end{center}
+ \end{minipage}
+
+ \begin{minipage}{3.8cm}
+ \begin{center}
+ \includegraphics[width=3.3cm]{sic_prec_seq_01.eps}
+ \end{center}
+ \end{minipage}
+ \hspace{0.6cm}
+ \begin{minipage}{3.8cm}
+ \begin{center}
+ \includegraphics[width=3.3cm]{sic_prec_seq_02.eps}
+ \end{center}
+ \end{minipage}
+ \hspace{0.6cm}
+ \begin{minipage}{3.8cm}
+ \begin{center}
+ \includegraphics[width=3.3cm]{sic_prec_seq_03.eps}
+ \end{center}
+ \end{minipage}
+
+\begin{pspicture}(0,0)(0,0)
+\psline[linewidth=4pt]{->}(8.5,2)(9.0,2)
+\psellipse[linecolor=blue](11.5,5.8)(0.3,0.5)
+\rput{-20}{\psellipse[linecolor=blue](3.3,8.1)(0.3,0.5)}
+\psline[linewidth=4pt]{->}(4.0,2)(4.5,2)
+\end{pspicture}
+
+\end{slide}
+
+\begin{slide}
+
+ {\large\bf
+ Basics of molecular dynamics (MD) simulations
+ }
+
+ \vspace{12pt}
+
+ \small
+
+ {\bf MD basics:}
+ \begin{itemize}
+ \item Microscopic description of N particle system
+ \item Analytical interaction potential
+ \item Numerical integration using Newtons equation of motion\\
+ as a propagation rule in 6N-dimensional phase space
+ \item Observables obtained by time and/or ensemble averages
+ \end{itemize}
+ {\bf Details of the simulation:}
+ \begin{itemize}
+ \item Integration: Velocity Verlet, timestep: $1\text{ fs}$
+ \item Ensemble: NpT (isothermal-isobaric)
+ \begin{itemize}
+ \item Berendsen thermostat:
+ $\tau_{\text{T}}=100\text{ fs}$
+ \item Berendsen barostat:\\
+ $\tau_{\text{P}}=100\text{ fs}$,
+ $\beta^{-1}=100\text{ GPa}$
+ \end{itemize}
+ \item Potential: Tersoff-like bond order potential
+ \vspace*{12pt}
+ \[
+ E = \frac{1}{2} \sum_{i \neq j} \pot_{ij}, \quad
+ \pot_{ij} = f_C(r_{ij}) \left[ f_R(r_{ij}) + b_{ij} f_A(r_{ij}) \right]
+ \]
+ \end{itemize}
+
+ \begin{picture}(0,0)(-230,-30)
+ \includegraphics[width=5cm]{tersoff_angle.eps}
+ \end{picture}
+
+\end{slide}
+
+\begin{slide}
+
+ {\large\bf
+ Basics of density functional theory (DFT) calculations
+ }
+
+ \small
+
+ Ingredients
+ \begin{itemize}
+ \item Hohenberg-Kohn (HK) theorem
+ \item \underline{Born-Oppenheimer}
+ - $N$ moving electrons in an external potential of static nuclei\\
+\[
+H\Psi = \left[-\sum_i^N \frac{\hbar^2}{2m}\nabla_i^2
+ +\sum_i^N V_{\text{ext}}(r_i)
+ +\sum_{i<j}^N V_{e-e}(r_i,r_j)\right]\Psi=E\Psi
+\]
+ \item \underline{Effective potential}
+ - replace electrostatic potential by an average over e$^-$ positions\\
+\[
+V_{\text{eff}}=...
+\]
+ \item Exchange correlation (EC) LDA / GGA
+ \item Self-consistent solution
+ \item Plane wave basis set
+ \item Pseudo potential
+ \end{itemize}
+
+\end{slide}
+
+
\end{document}
projects / lectures / latex.git / blobdiff