X-Git-Url: https://hackdaworld.org/gitweb/?a=blobdiff_plain;f=posic%2Fposter%2Femrs2008.tex;h=1226f1bda2a65b9f6d1db8f915b6bd89c2439989;hb=1690bbcc2a8510bb56499ac65a62b8a0fca251d6;hp=22e457b3dc0182c1a1235dc446c66b1897d68ab3;hpb=c14e26a07978bfdb0e10d2891168e8428f73e14b;p=lectures%2Flatex.git diff --git a/posic/poster/emrs2008.tex b/posic/poster/emrs2008.tex index 22e457b..1226f1b 100644 --- a/posic/poster/emrs2008.tex +++ b/posic/poster/emrs2008.tex @@ -22,6 +22,9 @@ \background{.40 .48 .71}{.99 .99 .99}{0.5} \newrgbcolor{si-yellow}{.6 .6 0} +\newrgbcolor{hb}{0.75 0.77 0.89} +\newrgbcolor{lbb}{0.75 0.8 0.88} +\newrgbcolor{lachs}{1.0 .93 .81} % Groesse der einzelnen Spalten als Anteil der Gesamt-Textbreite \renewcommand{\columnfrac}{.31} @@ -30,7 +33,7 @@ \newcommand{\pot}{\mathcal{V}} % header -\vspace{-18cm} +\vspace{-18.5cm} \begin{header} \centerline{{\Huge \bfseries Molecular dynamics simulation of defect formation and precipitation}} @@ -69,17 +72,19 @@ \begin{poster} -%\vspace{-6cm} +\vspace{-1cm} \begin{pcolumn} \begin{pbox} \section*{Motivation} - {\bf Reasons for understanding the 3C-SiC precipitation process} + {\bf Importance of the 3C-SiC precipitation process in silicon} \begin{itemize} - \item Significant technological progress - in 3C-SiC wide band gap semiconductor thin film formation [1]. - \item New perspectives for processes relying upon prevention of - precipitation, e.g. fabrication of strained pseudomorphic - $\text{Si}_{1-y}\text{C}_y$ heterostructures [2]. + \item SiC is a promising wide band gap material for high-temperature, + high-power, high-frequency semiconductor devices [1]. + \item 3C-SiC epitaxial thin film formation on Si requires detailed + knowledge of SiC nucleation. + \item Fabrication of high carbon doped, strained pseudomorphic + $\text{Si}_{1-y}\text{C}_y$ layers requires suppression of + 3C-SiC nucleation [2]. \end{itemize} {\tiny [1] J. H. Edgar, J. Mater. Res. 7 (1992) 235.}\\ @@ -87,6 +92,7 @@ [2] J. W. Strane, S. R. Lee, H. J. Stein, S. T. Picraux, J. K. Watanabe, J. W. Mayer, J. Appl. Phys. 79 (1996) 637.} \end{pbox} + \vspace{-0.45cm} \begin{pbox} \section*{Crystalline silicon and cubic silicon carbide} {\bf Lattice types and unit cells:} @@ -112,19 +118,18 @@ \includegraphics[width=10cm]{sic_unit_cell.eps} \end{minipage} \end{pbox} + \vspace{-0.45cm} \begin{pbox} \section*{Supposed Si to 3C-SiC conversion} {\bf Schematic of the conversion mechanism}\\\\ - \begin{minipage}{7.8cm} - \includegraphics[width=7.7cm]{sic_prec_seq_01.eps} + \begin{minipage}[c]{8.8cm} + \includegraphics[width=8.0cm]{sic_prec_seq_01.eps} \end{minipage} - \hspace{0.6cm} - \begin{minipage}{7.8cm} - \includegraphics[width=7.7cm]{sic_prec_seq_02.eps} + \begin{minipage}[c]{8.8cm} + \includegraphics[width=8.0cm]{sic_prec_seq_02.eps} \end{minipage} - \hspace{0.6cm} - \begin{minipage}{7.8cm} - \includegraphics[width=7.7cm]{sic_prec_seq_03.eps} + \begin{minipage}[c]{8.1cm} + \includegraphics[width=8.0cm]{sic_prec_seq_03.eps} \end{minipage} \vspace{1cm} \begin{enumerate} @@ -135,13 +140,14 @@ \vspace{1cm} {\bf Experimental observations} [3] \begin{itemize} - \item Minimal diameter of precipitation: 2 - 4 nm + \item Minimal radius of precipitates: 2 - 4 nm \item Equal orientation of c-Si and 3C-SiC (hkl)-planes \end{itemize} {\tiny [3] J. K. N. Lindner, Appl. Phys. A 77 (2003) 27. } \end{pbox} + \vspace{-0.45cm} \begin{pbox} \section*{Simulation details} {\bf MD basics:} @@ -190,7 +196,7 @@ \begin{minipage}{15cm} {\small \begin{pspicture}(0,0)(14,14) - \rput(7,12.5){\rnode{init}{\psframebox[fillstyle=solid,fillcolor=green]{ + \rput(7,12.5){\rnode{init}{\psframebox[fillstyle=solid,fillcolor=hb]{ \parbox{14cm}{ \begin{itemize} \item Initial configuration: $9\times9\times9$ unit cells Si @@ -212,7 +218,7 @@ \item random positions (critical distance check) \end{itemize} }}}} - \rput(7,1.5){\rnode{cool}{\psframebox[fillstyle=solid,fillcolor=cyan]{ + \rput(7,1.5){\rnode{cool}{\psframebox[fillstyle=solid,fillcolor=lbb]{ \parbox{7cm}{ Relaxation time: 2 ps }}}} @@ -280,7 +286,7 @@ \end{minipage}\\[1cm] } \begin{minipage}{17cm} -\underline{$<100>$ dumbbell configuration} +\underline{\flq100\frq{} dumbbell configuration} \begin{itemize} \item $E_f=0.47$ eV \item Very often observed @@ -292,7 +298,7 @@ \includegraphics[width=8cm]{c_in_si_int_001db_0.eps} \end{minipage}\\[1cm] \begin{center} -\includegraphics[width=24cm]{100-c-si-db_s.eps} +\includegraphics[width=26cm]{100-c-si-db_s.eps}\\[0.35cm] \end{center} {\tiny [6] G. D. Watkins and K. L. Brower, Phys. Rev. Lett. 36 (1976) 1329.} @@ -310,26 +316,26 @@ {\small \begin{pspicture}(0,0)(30,13) % nodes - \rput(7.5,11){\rnode{init}{\psframebox[fillstyle=solid,fillcolor=green]{ + \rput(7.5,11){\rnode{init}{\psframebox[fillstyle=solid,fillcolor=hb]{ \parbox{15cm}{ \begin{itemize} \item Initial configuration: $31\times31\times31$ unit cells Si \item Periodic boundary conditions \item $T=450\, ^{\circ}\textrm{C}$, $p=0\text{ bar}$ - \item Equilibration of $E_{kin}$ and $E_{pot}$ for 600 fs + \item Equilibration of $E_{kin}$ and $E_{pot}$ \end{itemize} }}}} - \rput(7.5,5){\rnode{insert}{\psframebox[fillstyle=solid,fillcolor=red]{ + \rput(7.5,5){\rnode{insert}{\psframebox[fillstyle=solid,fillcolor=lachs]{ \parbox{15cm}{ Insertion of 6000 carbon atoms at constant\\ - temperature into: + temperature into $V_1$ or $V_2$ or $V_3$: \begin{itemize} \item Total simulation volume $V_1$ \item Volume of minimal 3C-SiC precipitation $V_2$ \item Volume of necessary amount of Si $V_3$ \end{itemize} }}}} - \rput(7.5,1){\rnode{cool}{\psframebox[fillstyle=solid,fillcolor=cyan]{ + \rput(7.5,1){\rnode{cool}{\psframebox[fillstyle=solid,fillcolor=lbb]{ \parbox{8cm}{ Cooling down to $20\, ^{\circ}\textrm{C}$ }}}} @@ -355,55 +361,73 @@ \ncline[linewidth=0.05]{-}{in3}{in-3} \end{pspicture} } - - {\bf Results and interpretation:}\\ + {\bf Results:}\\ Si-C and C-C pair correlation function:\\ - \includegraphics[width=24cm]{pc_si-c_c-c.eps} + \hspace*{1.3cm} \includegraphics[width=22cm]{pc_si-c_c-c.eps} \begin{center} {\tiny {\bf Dashed vertical lines:} Further calculated C-Si distances - in the $<100>$ C-Si dumbbell interstitial configuration}\\[0.5cm] + in the \flq100\frq{} C-Si dumbbell interstitial configuration}\\[0.5cm] \end{center} Si-Si pair correlation function:\\ - \includegraphics[width=24cm]{pc_si-si.eps}\\ + \hspace*{1.3cm} \includegraphics[width=22cm]{pc_si-si.eps}\\ + {\bf Interpretation:} {\small \begin{itemize} \item C-C peak at 0.15 nm similar to next neighbour distance of graphite or diamond\\ $\Rightarrow$ Formation of strong C-C bonds (almost only for high C concentrations) + \item Si-C peak at 0.19 nm similar to next neighbour distance in 3C-SiC \item C-C peak at 0.31 nm equals C-C distance in 3C-SiC\\ (due to concatenated, differently oriented - $<100>$ dumbbell interstitials) - \item Si-Si shows non-zero g(r) values around 0.31 nm - and decrease at regular distances\\ + \flq100\frq{} dumbbell interstitials) + \item Si-Si shows non-zero g(r) values around 0.31 nm like in 3C-SiC\\ + and a decrease at regular distances\\ (no clear peak, interval of enhanced g(r) corresponds to C-C peak width) - \item Si-C peak at 0.19 nm similar to next neighbour distance in 3C-SiC - \item Low C concentration (i.e. $V_1$): The $<100>$ dumbbell configuration + \item Low C concentration (i.e. $V_1$): + The \flq100\frq{} dumbbell configuration \begin{itemize} \item is identified to stretch the Si-Si next neighbour distance to 0.3 nm \item is identified to contribute to the Si-C peak at 0.19 nm \item explains further C-Si peaks (dashed vertical lines) \end{itemize} + $\Rightarrow$ C atoms are first elements arranged at distances + expected for 3C-SiC\\ + $\Rightarrow$ C atoms pull the Si atoms into the right + configuration at a later stage \item High C concentration (i.e. $V_2$ and $V_3$): \begin{itemize} \item High amount of damage introduced into the system \item Short range order observed but almost no long range order \end{itemize} + $\Rightarrow$ Start of amorphous SiC-like phase formation\\ + $\Rightarrow$ Higher temperatures required for proper SiC formation \end{itemize} } \end{pbox} + \vspace{-2cm} \begin{pbox} - \section*{Conclusions} + \section*{Conclusion} \begin{itemize} - \item there should be - \item 3 conclusions - \item at least! + \item \flq100\frq{} C-Si dumbbell interstitial configuration is observed + to be the energetically most favorable configuration + \item For low C concentrations C atoms introduced as differently + oriented C-Si dumbbells in c-Si are properly arranged + for 3C-SiC formation + \item For high C concentrations an amorphous SiC-like phase is observed + which suggests higher temperature simulation runs for proper + 3C-SiC formation \end{itemize} \end{pbox} + \vspace{-2cm} + \begin{pbox} + One of us (F. Z.) wants to acknowledge financial support by the\\ + {\bf Bayerische Forschungsstiftung} (DPA-61/05). + \end{pbox} \end{pcolumn} \end{poster}