X-Git-Url: https://hackdaworld.org/gitweb/?p=lectures%2Flatex.git;a=blobdiff_plain;f=posic%2Ftalks%2Fmpi_app.tex;h=11274be50f7654cfd1b4f2c3fdb379a5f0545901;hp=2bf8383fd95ba5a487e0f7f27062a15681b7daf9;hb=b46804e27e8e7ee27ce2981a3664cfa97a8d2556;hpb=1c838933fa76951ad4deb1164e8d2a950b6771cf diff --git a/posic/talks/mpi_app.tex b/posic/talks/mpi_app.tex index 2bf8383..11274be 100644 --- a/posic/talks/mpi_app.tex +++ b/posic/talks/mpi_app.tex @@ -56,9 +56,14 @@ \usepackage{upgreek} +%\newrgbcolor{hred}{0.9 0.13 0.13} +%\newrgbcolor{hblue}{0.13 0.13 0.9} +\newrgbcolor{hred}{1.0 0.0 0.0} +\newrgbcolor{hblue}{0.0 0.0 1.0} + \newcommand{\headdiplom}{ \begin{pspicture}(0,0)(0,0) -\rput(6.0,0.2){\psframebox[fillstyle=gradient,gradbegin=red,gradend=white,gradlines=1000,gradmidpoint=1,linestyle=none]{ +\rput(6.0,0.2){\psframebox[fillstyle=gradient,gradbegin=hred,gradend=white,gradlines=1000,gradmidpoint=1,linestyle=none]{ \begin{minipage}{14cm} \hfill \vspace{0.7cm} @@ -69,7 +74,7 @@ \newcommand{\headphd}{ \begin{pspicture}(0,0)(0,0) -\rput(6.0,0.2){\psframebox[fillstyle=gradient,gradbegin=blue,gradend=white,gradlines=1000,gradmidpoint=1,linestyle=none]{ +\rput(6.0,0.2){\psframebox[fillstyle=gradient,gradbegin=hblue,gradend=white,gradlines=1000,gradmidpoint=1,linestyle=none]{ \begin{minipage}{14cm} \hfill \vspace{0.7cm} @@ -170,8 +175,6 @@ E\\ % no vertical centering \centerslidesfalse -\ifnum1=0 - % intro \begin{slide} @@ -427,7 +430,7 @@ Ion beam synthesis (IBS) of burried 3C-SiC layers in Si\hkl(1 0 0) \end{center} \begin{pspicture}(0,0)(0,0) -\rput(6.0,7.0){\rnode{init}{\psframebox[fillstyle=gradient,gradbegin=red,gradend=white,gradlines=1000,gradmidpoint=1.0,linestyle=none]{ +\rput(6.0,7.0){\rnode{init}{\psframebox[fillstyle=gradient,gradbegin=hred,gradend=white,gradlines=1000,gradmidpoint=1.0,linestyle=none]{ \begin{minipage}{11cm} {\color{black}Diploma thesis}\\ \underline{Monte Carlo} simulation modeling the selforganization process\\ @@ -436,7 +439,7 @@ Ion beam synthesis (IBS) of burried 3C-SiC layers in Si\hkl(1 0 0) }}} \end{pspicture} \begin{pspicture}(0,0)(0,0) -\rput(6.0,-0.5){\rnode{init}{\psframebox[fillstyle=gradient,gradbegin=blue,gradend=white,gradmidpoint=1.0,gradlines=1000,linestyle=none]{ +\rput(6.0,-0.5){\rnode{init}{\psframebox[fillstyle=gradient,gradbegin=hblue,gradend=white,gradmidpoint=1.0,gradlines=1000,linestyle=none]{ \begin{minipage}{11cm} {\color{black}Doctoral studies}\\ Classical potential \underline{molecular dynamics} simulations \ldots\\ @@ -583,7 +586,7 @@ p_{a \rightarrow c}(\vec r) = (1 - p_{c \rightarrow a}(\vec r)) \Big(1 - \frac{\ \begin{minipage}{3.7cm} \begin{pspicture}(0,0)(0,0) -\rput(1.7,0.2){\psframebox[fillstyle=gradient,gradbegin=red,gradend=white,gradlines=1000,gradangle=10,gradmidpoint=1,linestyle=none]{ +\rput(1.7,0.2){\psframebox[fillstyle=gradient,gradbegin=hred,gradend=white,gradlines=1000,gradangle=10,gradmidpoint=1,linestyle=none]{ \begin{minipage}{3.7cm} \hfill \vspace{0.7cm} @@ -1741,218 +1744,235 @@ Interaction along \hkl[1 1 0] \end{slide} -% continue here -\fi - \begin{slide} +\headphd {\large\bf - Defect combinations + Defect combinations of C-Si dimers and vacancies } - \footnotesize -\vspace{0.1cm} +\vspace{0.2cm} -{\bf Combinations of \ci{} \hkl[0 0 -1] and a vacancy}\\ -\begin{minipage}[t]{3cm} -\underline{Pos 2, $E_{\text{b}}=-0.59\text{ eV}$}\\ -\includegraphics[width=2.8cm]{00-1dc/0-59.eps} +\begin{minipage}[b]{2.6cm} +\begin{flushleft} +\underline{V at 2: $E_{\text{b}}=-0.59\text{ eV}$}\\[0.1cm] +\includegraphics[width=2.5cm]{00-1dc/0-59.eps} +\end{flushleft} \end{minipage} - - - -\begin{minipage}[t]{7cm} -\vspace{0.2cm} -\begin{center} - Low activation energies\\ - High activation energies for reverse processes\\ - $\Downarrow$\\ - {\color{blue}C$_{\text{sub}}$ very stable}\\ -\vspace*{0.1cm} - \hrule -\vspace*{0.1cm} - Without nearby \hkl<1 1 0> Si self-interstitial (IBS)\\ - $\Downarrow$\\ - {\color{blue}Formation of SiC by successive substitution by C} -\end{center} +\begin{minipage}[b]{7cm} +\hfill \end{minipage} +\begin{minipage}[b]{2.6cm} +\begin{flushright} +\underline{V at 3, $E_{\text{b}}=-3.14\text{ eV}$}\\[0.1cm] +\includegraphics[width=2.5cm]{00-1dc/3-14.eps} +\end{flushright} +\end{minipage}\\[0.2cm] - -\begin{minipage}[t]{3cm} -\underline{Pos 3, $E_{\text{b}}=-3.14\text{ eV}$}\\ -\includegraphics[width=2.8cm]{00-1dc/3-14.eps} +\begin{minipage}{6.5cm} +\includegraphics[width=6.0cm]{059-539.ps} +\end{minipage} +\begin{minipage}{5.7cm} +\includegraphics[width=6.0cm]{314-539.ps} \end{minipage} +\begin{pspicture}(0,0)(0,0) +\psline[linewidth=0.05cm,linecolor=gray](6.3,9.0)(6.3,0) -\framebox{ -\begin{minipage}{5.9cm} -\includegraphics[width=5.9cm]{vasp_mig/comb_mig_3-2_vac_fullct.ps}\\[0.6cm] +\rput(6.3,7.0){\rnode{init}{\psframebox[fillstyle=solid,fillcolor=white,linewidth=0.05cm,linecolor=gray]{ +\begin{minipage}{6.5cm} \begin{center} -\begin{picture}(0,0)(70,0) -\includegraphics[width=1.4cm]{vasp_mig/comb_2-1_init.eps} -\end{picture} -\begin{picture}(0,0)(30,0) -\includegraphics[width=1.4cm]{vasp_mig/comb_2-1_seq_03.eps} -\end{picture} -\begin{picture}(0,0)(-10,0) -\includegraphics[width=1.4cm]{vasp_mig/comb_2-1_seq_06.eps} -\end{picture} -\begin{picture}(0,0)(-48,0) -\includegraphics[width=1.4cm]{vasp_mig/comb_2-1_final.eps} -\end{picture} -\begin{picture}(0,0)(12.5,5) -\includegraphics[width=1cm]{100_arrow.eps} -\end{picture} -\begin{picture}(0,0)(97,-10) -\includegraphics[height=0.9cm]{001_arrow.eps} -\end{picture} -\end{center} -\vspace{0.1cm} -\end{minipage} +IBS: Impinging C creates V \& far away \si\\[0.3cm] +Low migration barrier towards C$_{\text{sub}}$\\ +\&\\ +High barrier for reverse process\\[0.3cm] +{\color{blue} +High probability of stable C$_{\text{sub}}$ configuration } -\begin{minipage}{0.3cm} -\hfill -\end{minipage} -\framebox{ -\begin{minipage}{5.9cm} -\includegraphics[width=5.9cm]{vasp_mig/comb_mig_4-2_vac_fullct.ps}\\[0.1cm] -\begin{center} -\begin{picture}(0,0)(60,0) -\includegraphics[width=0.9cm]{vasp_mig/comb_3-1_init.eps} -\end{picture} -\begin{picture}(0,0)(25,0) -\includegraphics[width=0.9cm]{vasp_mig/comb_3-1_seq_03.eps} -\end{picture} -\begin{picture}(0,0)(-20,0) -\includegraphics[width=0.9cm]{vasp_mig/comb_3-1_seq_07.eps} -\end{picture} -\begin{picture}(0,0)(-55,0) -\includegraphics[width=0.9cm]{vasp_mig/comb_3-1_final.eps} -\end{picture} -\begin{picture}(0,0)(12.5,5) -\includegraphics[width=1cm]{100_arrow.eps} -\end{picture} -\begin{picture}(0,0)(95,0) -\includegraphics[height=0.9cm]{001_arrow.eps} -\end{picture} \end{center} -\vspace{0.1cm} \end{minipage} -} +}}} +\end{pspicture} \end{slide} -\end{document} -\ifnum1=0 - \begin{slide} - {\large\bf\boldmath - Combinations of substitutional C and \hkl<1 1 0> Si self-interstitials - } - - \scriptsize +\headphd +{\large\bf + Combinations of substitutional C and Si self-interstitials +} -\begin{minipage}{6.0cm} -\includegraphics[width=5.8cm]{c_sub_si110.ps} -\end{minipage} -\begin{minipage}{7cm} \scriptsize + +\vspace{0.3cm} + +\begin{minipage}{6.2cm} +\begin{center} +{\bf\boldmath C$_{\text{sub}}$ - \si{} \hkl<1 1 0> interaction} \begin{itemize} - \item IBS: C may displace Si\\ - $\Rightarrow$ C$_{\text{sub}}$ + \hkl<1 1 0> Si self-interstitial - \item Assumption:\\ - \hkl<1 1 0>-type $\rightarrow$ favored combination - \renewcommand\labelitemi{$\Rightarrow$} - \item Most favorable: \cs{} along \hkl<1 1 0> chain \si{} - \item Less favorable than C-Si \hkl<1 0 0> dumbbell + \item Most favorable: \cs{} along \hkl<1 1 0> chain of \si{} + \item Less favorable than ground-state \ci{} \hkl<1 0 0> DB \item Interaction drops quickly to zero\\ $\rightarrow$ low capture radius \end{itemize} -\begin{center} - {\color{blue} - IBS process far from equilibrium\\ - \cs{} \& \si{} instead of thermodynamic ground state - } \end{center} \end{minipage} - -\begin{minipage}{6.5cm} -\includegraphics[width=6.0cm]{162-097.ps} +\begin{minipage}{0.2cm} +\hfill +\end{minipage} +\begin{minipage}{6.0cm} +\begin{center} +{\bf Transition from the ground state} \begin{itemize} - \item Low migration barrier + \item Low transition barrier + \item Barrier smaller than \ci{} migration barrier + \item Low \si{} migration barrier (\unit[0.67]{eV})\\ + $\rightarrow$ Separation of \cs{} \& \si{} most probable \end{itemize} +\end{center} +\end{minipage}\\[0.3cm] + +\begin{minipage}{6.0cm} +\includegraphics[width=6.0cm]{c_sub_si110.ps} \end{minipage} -\begin{minipage}{6.5cm} +\begin{minipage}{0.4cm} +\hfill +\end{minipage} +\begin{minipage}{6.0cm} +\begin{flushright} +\includegraphics[width=6.0cm]{162-097.ps} +\end{flushright} +\end{minipage} + +\begin{pspicture}(0,0)(0,0) +\psline[linewidth=0.05cm,linecolor=gray](6.5,0)(6.5,7.5) +\rput(6.5,-0.7){\rnode{init}{\psframebox[fillstyle=solid,fillcolor=white,linewidth=0.05cm,linecolor=blue]{ +\begin{minipage}{8cm} \begin{center} -Ab initio MD at \degc{900}\\ -\includegraphics[width=3.3cm]{md_vasp_01.eps} -$t=\unit[2230]{fs}$\\ -\includegraphics[width=3.3cm]{md_vasp_02.eps} -$t=\unit[2900]{fs}$ -\end{center} -{\color{blue} -Contribution of entropy to structural formation +\vspace{0.1cm} +{\color{black} +\cs{} \& \si{} instead of thermodynamic ground state\\[0.1cm] +IBS --- process far from equilibrium\\ } +\end{center} \end{minipage} +}}} +\end{pspicture} \end{slide} \begin{slide} - {\large\bf - Conclusion of defect / migration / combined defect simulations - } +\headphd +{\large\bf + Combinations of substitutional C and Si self-interstitials +} - \footnotesize +\scriptsize -\vspace*{0.1cm} +\vspace{0.3cm} -Defect structures +\begin{minipage}{6.2cm} +\begin{center} +{\bf\boldmath C$_{\text{sub}}$ - \si{} \hkl<1 1 0> interaction} \begin{itemize} - \item Accurately described by quantum-mechanical simulations - \item Less accurate description by classical potential simulations - \item Underestimated formation energy of \cs{} by classical approach - \item Both methods predict same ground state: \ci{} \hkl<1 0 0> dumbbell + \item Most favorable: \cs{} along \hkl<1 1 0> chain of \si{} + \item Less favorable than ground-state \ci{} \hkl<1 0 0> DB + \item Interaction drops quickly to zero\\ + $\rightarrow$ low capture radius \end{itemize} - -Migration -\begin{itemize} - \item C migration pathway in Si identified - \item Consistent with reorientation and diffusion experiments -\end{itemize} +\end{center} +\end{minipage} +\begin{minipage}{0.2cm} +\hfill +\end{minipage} +\begin{minipage}{6.0cm} +\begin{center} +{\bf Transition from the ground state} \begin{itemize} - \item Different path and ... - \item overestimated barrier by classical potential calculations -\end{itemize} + \item Low transition barrier + \item Barrier smaller than \ci{} migration barrier + \item Low \si{} migration barrier (\unit[0.67]{eV})\\ + $\rightarrow$ Separation of \cs{} \& \si{} most probable +\end{itemize} +\end{center} +\end{minipage}\\[0.3cm] -Concerning the precipitation mechanism -\begin{itemize} - \item Agglomeration of C-Si dumbbells energetically favorable - (stress compensation) - \item C-Si indeed favored compared to - C$_{\text{sub}}$ \& \hkl<1 1 0> Si self-interstitial - \item Possible low interaction capture radius of - C$_{\text{sub}}$ \& \hkl<1 1 0> Si self-interstitial - \item Low barrier for - \ci{} \hkl<1 0 0> $\rightarrow$ \cs{} \& \si{} \hkl<1 1 0> - \item In absence of nearby \hkl<1 1 0> Si self-interstitial: - C-Si \hkl<1 0 0> + Vacancy $\rightarrow$ C$_{\text{sub}}$ (SiC) -\end{itemize} +\begin{minipage}{6.0cm} +\includegraphics[width=6.0cm]{c_sub_si110.ps} +\end{minipage} +\begin{minipage}{0.4cm} +\hfill +\end{minipage} +\begin{minipage}{6.0cm} +\begin{flushright} +\includegraphics[width=6.0cm]{162-097.ps} +\end{flushright} +\end{minipage} + +\begin{pspicture}(0,0)(0,0) +\psline[linewidth=0.05cm,linecolor=gray](6.5,0)(6.5,7.5) +\rput(6.5,-0.7){\rnode{init}{\psframebox[fillstyle=solid,fillcolor=white,linewidth=0.05cm,linecolor=blue]{ +\begin{minipage}{8cm} \begin{center} -{\color{blue}Results suggest increased participation of \cs} +\vspace{0.1cm} +{\color{black} +\cs{} \& \si{} instead of thermodynamic ground state\\[0.1cm] +IBS --- process far from equilibrium\\ +} \end{center} +\end{minipage} +}}} +\end{pspicture} + +% md support +\begin{pspicture}(0,0)(0,0) +\rput(6.5,5.0){\psframebox[fillstyle=solid,opacity=0.5,fillcolor=black]{ +\begin{minipage}{14cm} +\hfill +\vspace{14cm} +\end{minipage} +}} +\rput(6.5,4.3){\rnode{init}{\psframebox[fillstyle=solid,fillcolor=white,linewidth=0.1cm]{ +\begin{minipage}{11cm} +\begin{center} +\vspace{0.2cm} +\scriptsize +Ab initio MD at \degc{900}\\[0.4cm] +\begin{minipage}{5.4cm} +\centering +\includegraphics[width=4.3cm]{md01_bonds.eps}\\ +$t=\unit[2230]{fs}$ +\end{minipage} +\begin{minipage}{5.4cm} +\centering +\includegraphics[width=4.3cm]{md02_bonds.eps}\\ +$t=\unit[2900]{fs}$ +\end{minipage}\\[0.5cm] +{\color{blue} +Contribution of entropy to structural formation\\[0.1cm] +} +\end{center} +\end{minipage} +}}} +\end{pspicture} \end{slide} \begin{slide} - {\large\bf - Silicon carbide precipitation simulations - } +\headphd +{\large\bf + Silicon carbide precipitation simulations +} - \small +\small + +\vspace{0.2cm} + +{\bf Procedure} {\scriptsize \begin{pspicture}(0,0)(12,6.5) @@ -1971,7 +1991,7 @@ Concerning the precipitation mechanism Insertion of C atoms at constant T \begin{itemize} \item total simulation volume {\pnode{in1}} - \item volume of minimal SiC precipitate {\pnode{in2}} + \item volume of minimal SiC precipitate size {\pnode{in2}} \item volume consisting of Si atoms to form a minimal {\pnode{in3}}\\ precipitate \end{itemize} @@ -1982,227 +2002,279 @@ Concerning the precipitation mechanism }}}} \ncline[]{->}{init}{insert} \ncline[]{->}{insert}{cool} - \psframe[fillstyle=solid,fillcolor=white](7.5,0.7)(13.5,6.3) - \rput(7.8,6){\footnotesize $V_1$} - \psframe[fillstyle=solid,fillcolor=lightgray](9,2)(12,5) - \rput(9.2,4.85){\tiny $V_2$} - \psframe[fillstyle=solid,fillcolor=gray](9.25,2.25)(11.75,4.75) - \rput(9.55,4.45){\footnotesize $V_3$} + \psframe[fillstyle=solid,fillcolor=white](7.3,0.7)(12.8,6.3) + \rput(7.6,6){\footnotesize $V_1$} + \psframe[fillstyle=solid,fillcolor=lightgray](8.7,2)(11.6,5) + \rput(8.9,4.85){\tiny $V_2$} + \psframe[fillstyle=solid,fillcolor=gray](8.95,2.25)(11.35,4.75) + \rput(9.25,4.45){\footnotesize $V_3$} \rput(7.9,3.2){\pnode{ins1}} - \rput(9.22,2.8){\pnode{ins2}} - \rput(11.0,2.4){\pnode{ins3}} + \rput(8.92,2.8){\pnode{ins2}} + \rput(10.8,2.4){\pnode{ins3}} \ncline[]{->}{in1}{ins1} \ncline[]{->}{in2}{ins2} \ncline[]{->}{in3}{ins3} \end{pspicture} } +\vspace{-0.5cm} + +{\bf Note} + +\footnotesize + +\begin{minipage}{5.7cm} \begin{itemize} - \item Restricted to classical potential simulations - \item $V_2$ and $V_3$ considered due to low diffusion - \item Amount of C atoms: 6000 - ($r_{\text{prec}}\approx 3.1\text{ nm}$, IBS: 2 ... 4 nm) - \item Simulation volume: $31\times 31\times 31$ unit cells + \item Amount of C atoms: 6000\\ + ($r_{\text{prec}}\approx 3.1\text{ nm}$, IBS: \unit[2--4]{nm}) + \item Simulation volume: $31^3$ Si unit cells\\ (238328 Si atoms) \end{itemize} +\end{minipage} +\begin{minipage}{0.3cm} +\hfill +\end{minipage} +\framebox{ +\begin{minipage}{6.0cm} +Restricted to classical potential caclulations\\ +$\rightarrow$ Low C diffusion / overestimated barrier\\ +$\rightarrow$ Consider $V_2$ and $V_3$ +%\begin{itemize} +% \item $V_2$ and $V_3$ considered due to expected low C diffusion +%\end{itemize} +\end{minipage} +} \end{slide} \begin{slide} - {\large\bf\boldmath - Silicon carbide precipitation simulations at $450\,^{\circ}\mathrm{C}$ as in IBS - } - - \small +\headphd +{\large\bf\boldmath + Silicon carbide precipitation simulations at \degc{450} as in IBS +} -\begin{minipage}{6.5cm} -\includegraphics[width=6.4cm]{sic_prec_450_si-si_c-c.ps} -\end{minipage} -\begin{minipage}{6.5cm} -\includegraphics[width=6.4cm]{sic_prec_450_energy.ps} -\end{minipage} +\small -\begin{minipage}{6.5cm} -\includegraphics[width=6.4cm]{sic_prec_450_si-c.ps} +\begin{minipage}{6.3cm} +\hspace*{-0.4cm}\includegraphics[width=6.5cm]{sic_prec_450_si-c.ps}\\ +\hspace*{-0.4cm}\includegraphics[width=6.5cm]{sic_prec_450_si-si_c-c.ps} +\hfill \end{minipage} -\begin{minipage}{6.5cm} +\begin{minipage}{6.1cm} \scriptsize -\underline{Low C concentration ($V_1$)}\\ +\underline{Low C concentration --- {\color{red}$V_1$}}\\[0.1cm] \hkl<1 0 0> C-Si dumbbell dominated structure \begin{itemize} - \item Si-C bumbs around 0.19 nm - \item C-C peak at 0.31 nm (as expected in 3C-SiC):\\ - concatenated dumbbells of various orientation - \item Si-Si NN distance stretched to 0.3 nm + \item Si-C bumbs around \unit[0.19]{nm} + \item C-C peak at \unit[0.31]{nm} (expected in 3C-SiC):\\ + concatenated differently oriented \ci{} DBs + \item Si-Si NN distance stretched to \unit[0.3]{nm} +\end{itemize} +\begin{pspicture}(0,0)(6.0,1.0) +\rput(3.2,0.5){\psframebox[linewidth=0.03cm,linecolor=blue]{ +\begin{minipage}{6cm} +\centering +Formation of \ci{} dumbbells\\ +C atoms in proper 3C-SiC distance first +\end{minipage} +}} +\end{pspicture}\\[0.1cm] +\underline{High C concentration --- {\color{green}$V_2$}/{\color{blue}$V_3$}} +\begin{itemize} +\item High amount of strongly bound C-C bonds +\item Increased defect \& damage density\\ + $\rightarrow$ Arrangements hard to categorize and trace +\item Only short range order observable \end{itemize} -{\color{blue}$\Rightarrow$ C atoms in proper 3C-SiC distance first}\\ -\underline{High C concentration ($V_2$, $V_3$)}\\ -High amount of strongly bound C-C bonds\\ -Defect density $\uparrow$ $\Rightarrow$ considerable amount of damage\\ -Only short range order observable\\ -{\color{blue}$\Rightarrow$ amorphous SiC-like phase} +\begin{pspicture}(0,0)(6.0,0.8) +\rput(3.2,0.5){\psframebox[linewidth=0.03cm,linecolor=blue]{ +\begin{minipage}{6cm} +\centering +Amorphous SiC-like phase +\end{minipage} +}} +\end{pspicture}\\[0.3cm] +\begin{pspicture}(0,0)(6.0,2.0) +\rput(3.2,1.0){\psframebox[linewidth=0.05cm,linecolor=white]{ +\begin{minipage}{6cm} +\hfill +\vspace{2.5cm} +\end{minipage} +}} +\end{pspicture} \end{minipage} \end{slide} \begin{slide} - {\large\bf\boldmath - Silicon carbide precipitation simulations at $450\,^{\circ}\mathrm{C}$ as in IBS - } - - \small +\headphd +{\large\bf\boldmath + Silicon carbide precipitation simulations at \degc{450} as in IBS +} -\begin{minipage}{6.5cm} -\includegraphics[width=6.4cm]{sic_prec_450_si-si_c-c.ps} -\end{minipage} -\begin{minipage}{6.5cm} -\includegraphics[width=6.4cm]{sic_prec_450_energy.ps} -\end{minipage} +\small -\begin{minipage}{6.5cm} -\includegraphics[width=6.4cm]{sic_prec_450_si-c.ps} +\begin{minipage}{6.3cm} +\hspace*{-0.4cm}\includegraphics[width=6.5cm]{sic_prec_450_si-c.ps}\\ +\hspace*{-0.4cm}\includegraphics[width=6.5cm]{sic_prec_450_si-si_c-c.ps} +\hfill \end{minipage} -\begin{minipage}{6.5cm} +\begin{minipage}{6.1cm} \scriptsize -\underline{Low C concentration ($V_1$)}\\ +\underline{Low C concentration --- {\color{red}$V_1$}}\\[0.1cm] \hkl<1 0 0> C-Si dumbbell dominated structure \begin{itemize} - \item Si-C bumbs around 0.19 nm - \item C-C peak at 0.31 nm (as expected in 3C-SiC):\\ - concatenated dumbbells of various orientation - \item Si-Si NN distance stretched to 0.3 nm + \item Si-C bumbs around \unit[0.19]{nm} + \item C-C peak at \unit[0.31]{nm} (expected in 3C-SiC):\\ + concatenated differently oriented \ci{} DBs + \item Si-Si NN distance stretched to \unit[0.3]{nm} \end{itemize} -{\color{blue}$\Rightarrow$ C atoms in proper 3C-SiC distance first}\\ -\underline{High C concentration ($V_2$, $V_3$)}\\ -High amount of strongly bound C-C bonds\\ -Defect density $\uparrow$ $\Rightarrow$ considerable amount of damage\\ -Only short range order observable\\ -{\color{blue}$\Rightarrow$ amorphous SiC-like phase} -\end{minipage} - -\begin{pspicture}(0,0)(0,0) -\rput(6.7,5.2){\rnode{init}{\psframebox[fillstyle=solid,fillcolor=white]{ -\begin{minipage}{10cm} -\small -{\color{red}\bf 3C-SiC formation fails to appear} +\begin{pspicture}(0,0)(6.0,1.0) +\rput(3.2,0.5){\psframebox[linewidth=0.03cm,linecolor=blue]{ +\begin{minipage}{6cm} +\centering +Formation of \ci{} dumbbells\\ +C atoms in proper 3C-SiC distance first +\end{minipage} +}} +\end{pspicture}\\[0.1cm] +\underline{High C concentration --- {\color{green}$V_2$}/{\color{blue}$V_3$}} \begin{itemize} -\item Low C concentration simulations - \begin{itemize} - \item Formation of \ci{} indeed occurs - \item Agllomeration not observed - \end{itemize} -\item High C concentration simulations - \begin{itemize} - \item Amorphous SiC-like structure\\ - (not expected at prevailing temperatures) - \item Rearrangement and transition into 3C-SiC structure missing - \end{itemize} +\item High amount of strongly bound C-C bonds +\item Increased defect \& damage density\\ + $\rightarrow$ Arrangements hard to categorize and trace +\item Only short range order observable \end{itemize} +\begin{pspicture}(0,0)(6.0,0.8) +\rput(3.2,0.5){\psframebox[linewidth=0.03cm,linecolor=blue]{ +\begin{minipage}{6cm} +\centering +Amorphous SiC-like phase \end{minipage} - }}} +}} +\end{pspicture}\\[0.3cm] +\begin{pspicture}(0,0)(6.0,2.0) +\rput(3.2,1.0){\psframebox[linewidth=0.05cm,linecolor=black]{ +\begin{minipage}{6cm} +\vspace{0.1cm} +\centering +{\bf\color{red}3C-SiC formation fails to appear}\\[0.3cm] +\begin{minipage}{0.8cm} +{\bf\boldmath $V_1$:} +\end{minipage} +\begin{minipage}{5.1cm} +Formation of \ci{} indeed occurs\\ +Agllomeration not observed +\end{minipage}\\[0.3cm] +\begin{minipage}{0.8cm} +{\bf\boldmath $V_{2,3}$:} +\end{minipage} +\begin{minipage}{5.1cm} +Amorphous SiC-like structure\\ +(not expected at \degc{450})\\[0.05cm] +No rearrangement/transition into 3C-SiC +\end{minipage}\\[0.1cm] +\end{minipage} +}} \end{pspicture} +\end{minipage} \end{slide} \begin{slide} - {\large\bf - Limitations of molecular dynamics and short range potentials - } +\headphd +{\large\bf + Limitations of MD and short range potentials +} -\footnotesize +\small \vspace{0.2cm} -\underline{Time scale problem of MD}\\[0.2cm] -Minimize integration error\\ -$\Rightarrow$ discretization considerably smaller than - reciprocal of fastest vibrational mode\\[0.1cm] -Order of fastest vibrational mode: $10^{13} - 10^{14}\text{ Hz}$\\ -$\Rightarrow$ suitable choice of time step: - $\tau=1\text{ fs}=10^{-15}\text{ s}$\\ -$\Rightarrow$ {\color{red}\underline{slow}} phase space propagation\\[0.1cm] -Several local minima in energy surface separated by large energy barriers\\ -$\Rightarrow$ transition event corresponds to a multiple +{\bf Time scale problem of MD}\\[0.2cm] +Precise integration \& thermodynamic sampling\\ +$\Rightarrow$ $\Delta t \ll \left( \max{\omega} \right)^{-1}$, + $\omega$: vibrational mode\\ +$\Rightarrow$ {\color{red}\underline{Slow}} phase space propagation\\[0.2cm] +Several local minima separated by large energy barriers\\ +$\Rightarrow$ Transition event corresponds to a multiple of vibrational periods\\ -$\Rightarrow$ phase transition made up of {\color{red}\underline{many}} - infrequent transition events\\[0.1cm] +$\Rightarrow$ Phase transition consists of {\color{red}\underline{many}} + infrequent transition events\\[0.2cm] {\color{blue}Accelerated methods:} \underline{Temperature accelerated} MD (TAD), self-guided MD \ldots -\vspace{0.3cm} - -\underline{Limitations related to the short range potential}\\[0.2cm] -Cut-off function pushing forces and energies to zero between 1$^{\text{st}}$ -and 2$^{\text{nd}}$ next neighbours\\ -$\Rightarrow$ overestimated unphysical high forces of next neighbours - -\vspace{0.3cm} +\vspace{0.2cm} -\framebox{ -\color{red} -Potential enhanced problem of slow phase space propagation -} +{\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) -\vspace{0.3cm} +\vspace{1.4cm} -\underline{Approach to the (twofold) problem}\\[0.2cm] +{\bf Approach to the (twofold) problem}\\[0.2cm] Increased temperature simulations without TAD corrections\\ -(accelerated methods or higher time scales exclusively not sufficient) +Accelerated methods or higher time scales exclusively not sufficient! -\begin{picture}(0,0)(-260,-30) -\framebox{ -\begin{minipage}{4.2cm} -\tiny -\begin{center} -\vspace{0.03cm} -\underline{IBS} -\end{center} -\begin{itemize} -\item 3C-SiC also observed for higher T -\item higher T inside sample -\item structural evolution vs.\\ - equilibrium properties -\end{itemize} +\begin{pspicture}(0,0)(0,0) +\rput(4.0,2.8){\psframebox[linewidth=0.07cm,linecolor=red]{ +\begin{minipage}{7.5cm} +\centering +\vspace{0.05cm} +Potential enhanced slow phase space propagation \end{minipage} -} -\end{picture} - -\begin{picture}(0,0)(-305,-155) -\framebox{ -\begin{minipage}{2.5cm} +}} +\rput(11.3,7.5){\psframebox[linewidth=0.03cm,linecolor=blue]{ +\begin{minipage}{2.7cm} \tiny -\begin{center} +\centering retain proper\\ -thermodynmic sampling -\end{center} +thermodynamic sampling \end{minipage} -} -\end{picture} +}} +\psline[linewidth=0.03cm,linecolor=blue]{<-}(11.3,7.0)(11.0,5.7) +\rput(10.85,2.6){\psframebox[linewidth=0.03cm,linecolor=blue]{ +\begin{minipage}{3.6cm} +\tiny +\centering +\underline{IBS}\\[0.1cm] +3C-SiC also observed for higher T\\[0.1cm] +Higher T inside sample\\[0.1cm] +Structural evolution vs.\\ +equilibrium properties +\end{minipage} +}} +\psline[linewidth=0.03cm,linecolor=blue]{->}(10.85,1.75)(9.0,1.0) +\end{pspicture} \end{slide} \begin{slide} - {\large\bf - Increased temperature simulations at low C concentration - } +\headphd +{\large\bf\boldmath + Increased temperature simulations --- $V_1$ +} \small -\begin{minipage}{6.5cm} -\includegraphics[width=6.4cm]{tot_pc_thesis.ps} +\begin{minipage}{6.2cm} +\hspace*{-0.4cm}\includegraphics[width=6.5cm]{tot_pc_thesis.ps} +\hfill \end{minipage} -\begin{minipage}{6.5cm} -\includegraphics[width=6.4cm]{tot_pc3_thesis.ps} +\begin{minipage}{6.2cm} +\includegraphics[width=6.5cm]{tot_pc3_thesis.ps} \end{minipage} -\begin{minipage}{6.5cm} -\includegraphics[width=6.4cm]{tot_pc2_thesis.ps} +\begin{minipage}{6.2cm} +\hspace*{-0.4cm}\includegraphics[width=6.5cm]{tot_pc2_thesis.ps} +\hfill \end{minipage} -\begin{minipage}{6.5cm} +\begin{minipage}{6.3cm} \scriptsize \underline{Si-C bonds:} \begin{itemize} @@ -2229,40 +2301,30 @@ thermodynmic sampling \end{itemize} \end{minipage} -\begin{picture}(0,0)(-330,-74) -\color{blue} -\framebox{ -\begin{minipage}{1.6cm} -\tiny -\begin{center} -stretched SiC\\[-0.1cm] -in c-Si -\end{center} -\end{minipage} -} -\end{picture} - \end{slide} \begin{slide} - {\large\bf - Increased temperature simulations at low C concentration - } +\headphd +{\large\bf\boldmath + Increased temperature simulations --- $V_1$ +} \small -\begin{minipage}{6.5cm} -\includegraphics[width=6.4cm]{tot_pc_thesis.ps} +\begin{minipage}{6.2cm} +\hspace*{-0.4cm}\includegraphics[width=6.5cm]{tot_pc_thesis.ps} +\hfill \end{minipage} -\begin{minipage}{6.5cm} -\includegraphics[width=6.4cm]{tot_pc3_thesis.ps} +\begin{minipage}{6.2cm} +\includegraphics[width=6.5cm]{tot_pc3_thesis.ps} \end{minipage} -\begin{minipage}{6.5cm} -\includegraphics[width=6.4cm]{tot_pc2_thesis.ps} +\begin{minipage}{6.2cm} +\hspace*{-0.4cm}\includegraphics[width=6.5cm]{tot_pc2_thesis.ps} +\hfill \end{minipage} -\begin{minipage}{6.5cm} +\begin{minipage}{6.3cm} \scriptsize \underline{Si-C bonds:} \begin{itemize} @@ -2289,40 +2351,58 @@ in c-Si \end{itemize} \end{minipage} -%\begin{picture}(0,0)(-330,-74) -%\color{blue} -%\framebox{ -%\begin{minipage}{1.6cm} -%\tiny -%\begin{center} -%stretched SiC\\[-0.1cm] -%in c-Si -%\end{center} -%\end{minipage} -%} -%\end{picture} - +% conclusions \begin{pspicture}(0,0)(0,0) -\rput(6.7,5.2){\rnode{init}{\psframebox[fillstyle=solid,fillcolor=white]{ -\begin{minipage}{10cm} +\rput(6.5,5.0){\psframebox[fillstyle=solid,opacity=0.5,fillcolor=black]{ +\begin{minipage}{14cm} +\hfill +\vspace{14cm} +\end{minipage} +}} +\rput(6.5,5.0){\psframebox[fillstyle=solid,fillcolor=white,linewidth=0.1cm]{ +\begin{minipage}{9cm} +\vspace{0.2cm} \small -{\color{blue}\bf Stretched SiC in c-Si} +\begin{center} +{\color{gray}\bf Conclusions on SiC precipitation}\\[0.1cm] +{\Huge$\lightning$} {\color{red}\ci{}} --- vs --- {\color{blue}\cs{}} {\Huge$\lightning$}\\ +\end{center} \begin{itemize} -\item Consistent to precipitation model involving \cs{} -\item Explains annealing behavior of high/low T C implants +\item Stretched coherent SiC structures\\ +$\Rightarrow$ Precipitation process involves {\color{blue}\cs} +\item Explains annealing behavior of high/low T C implantations + \begin{itemize} + \item Low T: highly mobile {\color{red}\ci} + \item High T: stable configurations of {\color{blue}\cs} + \end{itemize} +\item Role of \si{} \begin{itemize} - \item Low T: highly mobiel \ci{} - \item High T: stable configurations of \cs{} + \item Vehicle to rearrange \cs --- [\cs{} \& \si{} $\leftrightarrow$ \ci] + \item Building block for surrounding Si host \& further SiC + \item Strain compensation \ldots\\ + \ldots Si/SiC interface\\ + \ldots within stretched coherent SiC structure \end{itemize} \end{itemize} -$\Rightarrow$ High T $\leftrightarrow$ IBS conditions far from equilibrium\\ -$\Rightarrow$ Precipitation mechanism involving \cs{} +\vspace{0.2cm} +\centering +\psframebox[linecolor=blue,linewidth=0.05cm]{ +\begin{minipage}{7cm} +\centering +Precipitation mechanism involving \cs\\ +High T $\leftrightarrow$ IBS conditions far from equilibrium\\ \end{minipage} - }}} +} +\end{minipage} +\vspace{0.2cm} +}} \end{pspicture} \end{slide} +% skip high T / C conc ... only here! +\ifnum1=0 + \begin{slide} {\large\bf @@ -2389,68 +2469,56 @@ High C \& low T implants \end{slide} -\begin{slide} +% skipped high T / C conc +\fi - {\large\bf - Summary and Conclusions - } +\begin{slide} - \scriptsize +{\large\bf + Summary / Outlook +} -%\vspace{0.1cm} +\small -\framebox{ -\begin{minipage}[t]{12.9cm} - \underline{Pecipitation simulations} - \begin{itemize} - \item High C concentration $\rightarrow$ amorphous SiC like phase - \item Problem of potential enhanced slow phase space propagation - \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 Precipitation by successive agglomeration of \cs (epitaxy) - \item \si{}: vehicle to form \cs{} \& supply of Si \& stress compensation - (stretched SiC, interface) - \end{itemize} +\begin{pspicture}(0,0)(12,1.0) +\psframebox[fillstyle=gradient,gradbegin=hred,gradend=white,gradlines=1000,gradmidpoint=1.0,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} } - -%\vspace{0.1cm} - -\framebox{ -\begin{minipage}{12.9cm} - \underline{Defects} - \begin{itemize} - \item DFT / EA - \begin{itemize} - \item Point defects excellently / fairly well described - by DFT / EA - \item C$_{\text{sub}}$ drastically underestimated by EA - \item EA predicts correct ground state: - C$_{\text{sub}}$ \& \si{} $>$ \ci{} - \item Identified migration path explaining - diffusion and reorientation experiments by DFT - \item EA fails to describe \ci{} migration: - Wrong path \& overestimated barrier - \end{itemize} - \item Combinations of defects - \begin{itemize} - \item Agglomeration of point defects energetically favorable - by compensation of stress - \item Formation of C-C unlikely - \item C$_{\text{sub}}$ favored conditions (conceivable in IBS) - \item \ci{} \hkl<1 0 0> $\leftrightarrow$ \cs{} \& \si{} \hkl<1 1 0>\\ - Low barrier (\unit[0.77]{eV}) \& low capture radius - \end{itemize} - \end{itemize} +\end{pspicture}\\[0.4cm] +\begin{pspicture}(0,0)(12,2) +\psframebox[fillstyle=gradient,gradbegin=hblue,gradend=white,gradmidpoint=1.0,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} } - -\begin{center} -{\color{blue} -\framebox{Precipitation by successive agglomeration of \cs{}} +\end{pspicture}\\[0.5cm] +\begin{pspicture}(0,0)(12,3) +\psframebox[fillstyle=solid,fillcolor=white,linestyle=solid]{ +\begin{minipage}{11cm} +\vspace{0.2cm} +{\color{black}\bf How to proceed \ldots}\\[0.1cm] +MC $\rightarrow$ empirical potential MD $\rightarrow$ Ground-state DFT \ldots +\begin{itemize} + \renewcommand\labelitemi{$\ldots$} + \item beyond LDA/GGA methods \& ground-state DFT +\end{itemize} +Investigation of structure \& structural evolution \ldots +\begin{itemize} + \renewcommand\labelitemi{$\ldots$} + \item electronic/optical properties + \item electronic correlations + \item non-equilibrium systems +\end{itemize} +\end{minipage} } -\end{center} +\end{pspicture}\\[0.5cm] \end{slide} @@ -2502,4 +2570,3 @@ High C \& low T implants \end{document} -\fi