From 918b064821da48aed61c671f936f699d7a14edae Mon Sep 17 00:00:00 2001 From: hackbard Date: Thu, 26 May 2011 15:33:52 +0200 Subject: [PATCH] seminar 2011 ... --- posic/talks/seminar_2011.tex | 356 +++++++++++++++++++++++++++-------- 1 file changed, 277 insertions(+), 79 deletions(-) diff --git a/posic/talks/seminar_2011.tex b/posic/talks/seminar_2011.tex index 2499073..ca198d5 100644 --- a/posic/talks/seminar_2011.tex +++ b/posic/talks/seminar_2011.tex @@ -397,6 +397,7 @@ Thermal conductivity [W/cmK] & 5.0 & 4.9 & 4.9 & 1.5 & 1.3 & 22 \\ \end{slide} + \begin{slide} {\large\bf @@ -565,20 +566,26 @@ r = 2 - 4 nm \rput(9.7,6.2){\rnode{init}{\psframebox[fillstyle=solid,fillcolor=hb]{ r = 2 - 4 nm }}} -\rput(6.7,6.2){\rnode{init}{\psframebox[fillstyle=solid,fillcolor=lachs]{ +\rput(6.7,5.2){\rnode{init}{\psframebox[fillstyle=solid,fillcolor=white]{ \begin{minipage}{10cm} \small -IBS studies revealing controversial views\\ +{\color{red}\bf Controversial views} \begin{itemize} -\item Nejim et al. +\item Implantations at high T (Nejim et al.) \begin{itemize} \item Topotactic transformation based on \cs - \item \si as supply reacting with further C in cleared volume + \item \si{} as supply reacting with further C in cleared volume + \end{itemize} +\item Annealing behavior (Serre et al.) + \begin{itemize} + \item Room temperature implants $\rightarrow$ highly mobile C + \item Elevated T implants $\rightarrow$ no/low C redistribution/migration\\ + (indicate stable \cs{} configurations) \end{itemize} -\item Serre, Reeson, Lindner ... +\item Strained silicon \& Si/SiC heterostructures \begin{itemize} - \item RT implants: highly mobile C - \item elevated T implants: no/low C redistribution/migration + \item Coherent SiC precipitates (tensile strain) + \item Incoherent SiC (strain relaxation) \end{itemize} \end{itemize} \end{minipage} @@ -620,7 +627,8 @@ IBS studies revealing controversial views\\ \vspace*{12pt} \[ E = \frac{1}{2} \sum_{i \neq j} \pot_{ij}, \quad - \pot_{ij} = f_C(r_{ij}) \left[ f_R(r_{ij}) + b_{ij} f_A(r_{ij}) \right] + \pot_{ij} = {\color{red}f_C(r_{ij})} + \left[ f_R(r_{ij}) + {\color{blue}b_{ij}} f_A(r_{ij}) \right] \] \end{itemize} @@ -1420,6 +1428,10 @@ Transition involving \ci{} \hkl<1 1 0> \item 2.4 - 3.4 times higher than VASP \item Rotation of dumbbell orientation \end{itemize} +\vspace{0.1cm} +\begin{center} +{\color{blue}Overestimated diffusion barrier} +\end{center} \end{minipage} \end{minipage} @@ -1478,14 +1490,16 @@ $ \end{minipage} \begin{minipage}[t]{5.5cm} \begin{itemize} - \item Restricted to VASP simulations - \item $E_{\text{b}}=0$ for isolated non-interacting defects - \item $E_{\text{b}} \rightarrow 0$ for increasing distance (R) + \item $E_{\text{b}}=0$ $\Leftrightarrow$ non-interacting defects\\ + $E_{\text{b}} \rightarrow 0$ for increasing distance (R) \item Stress compensation / increase - \item Most favorable: C clustering \item Unfavored: antiparallel orientations \item Indication of energetically favored\\ agglomeration + \item Most favorable: C clustering + \item However: High barrier ($>4\,\text{eV}$) + \item $4\times{\color{cyan}-2.25}$ versus $2\times{\color{orange}-2.39}$ + (Entropy) \end{itemize} \end{minipage} @@ -1527,11 +1541,17 @@ Type & \hkl<-1 0 0> & \hkl<1 0 0> & \hkl<1 0 0> & \hkl<1 0 0> & \hkl<1 0 0> & \h \includegraphics[width=7cm]{db_along_110_cc.ps} \end{minipage} \begin{minipage}{6.0cm} +\begin{itemize} + \item Interaction proportional to reciprocal cube of C-C distance + \item Saturation in the immediate vicinity + \renewcommand\labelitemi{$\Rightarrow$} + \item Agglomeration of \ci{} expected + \item Absence of C clustering +\end{itemize} \begin{center} {\color{blue} - Interaction proportional to reciprocal cube of C-C distance -}\\[0.2cm] - Saturation in the immediate vicinity + Consisten with initial precipitation model +} \end{center} \end{minipage} @@ -1547,54 +1567,79 @@ Type & \hkl<-1 0 0> & \hkl<1 0 0> & \hkl<1 0 0> & \hkl<1 0 0> & \hkl<1 0 0> & \h \scriptsize -\begin{center} -\begin{minipage}{3.2cm} -\includegraphics[width=3cm]{sub_110_combo.eps} -\end{minipage} -\begin{minipage}{7.8cm} -\begin{tabular}{l c c c c c c} -\hline -C$_{\text{sub}}$ & \hkl<1 1 0> & \hkl<-1 1 0> & \hkl<0 1 1> & \hkl<0 -1 1> & - \hkl<1 0 1> & \hkl<-1 0 1> \\ -\hline -1 & \RM{1} & \RM{3} & \RM{3} & \RM{1} & \RM{3} & \RM{1} \\ -2 & \RM{2} & A & A & \RM{2} & C & \RM{5} \\ -3 & \RM{3} & \RM{1} & \RM{3} & \RM{1} & \RM{1} & \RM{3} \\ -4 & \RM{4} & B & D & E & E & D \\ -5 & \RM{5} & C & A & \RM{2} & A & \RM{2} \\ -\hline -\end{tabular} -\end{minipage} -\end{center} +%\begin{center} +%\begin{minipage}{3.2cm} +%\includegraphics[width=3cm]{sub_110_combo.eps} +%\end{minipage} +%\begin{minipage}{7.8cm} +%\begin{tabular}{l c c c c c c} +%\hline +%C$_{\text{sub}}$ & \hkl<1 1 0> & \hkl<-1 1 0> & \hkl<0 1 1> & \hkl<0 -1 1> & +% \hkl<1 0 1> & \hkl<-1 0 1> \\ +%\hline +%1 & \RM{1} & \RM{3} & \RM{3} & \RM{1} & \RM{3} & \RM{1} \\ +%2 & \RM{2} & A & A & \RM{2} & C & \RM{5} \\ +%3 & \RM{3} & \RM{1} & \RM{3} & \RM{1} & \RM{1} & \RM{3} \\ +%4 & \RM{4} & B & D & E & E & D \\ +%5 & \RM{5} & C & A & \RM{2} & A & \RM{2} \\ +%\hline +%\end{tabular} +%\end{minipage} +%\end{center} -\begin{center} -\begin{tabular}{l c c c c c c c c c c} -\hline -Conf & \RM{1} & \RM{2} & \RM{3} & \RM{4} & \RM{5} & A & B & C & D & E \\ -\hline -$E_{\text{f}}$ [eV]& 4.37 & 5.26 & 5.57 & 5.37 & 5.12 & 5.10 & 5.32 & 5.28 & 5.39 & 5.32 \\ -$E_{\text{b}}$ [eV] & -0.97 & -0.08 & 0.22 & -0.02 & -0.23 & -0.25 & -0.02 & -0.06 & 0.05 & -0.03 \\ -$r$ [nm] & 0.292 & 0.394 & 0.241 & 0.453 & 0.407 & 0.408 & 0.452 & 0.392 & 0.456 & 0.453\\ -\hline -\end{tabular} -\end{center} +%\begin{center} +%\begin{tabular}{l c c c c c c c c c c} +%\hline +%Conf & \RM{1} & \RM{2} & \RM{3} & \RM{4} & \RM{5} & A & B & C & D & E \\ +%\hline +%$E_{\text{f}}$ [eV]& 4.37 & 5.26 & 5.57 & 5.37 & 5.12 & 5.10 & 5.32 & 5.28 & 5.39 & 5.32 \\ +%$E_{\text{b}}$ [eV] & -0.97 & -0.08 & 0.22 & -0.02 & -0.23 & -0.25 & -0.02 & -0.06 & 0.05 & -0.03 \\ +%$r$ [nm] & 0.292 & 0.394 & 0.241 & 0.453 & 0.407 & 0.408 & 0.452 & 0.392 & 0.456 & 0.453\\ +%\hline +%\end{tabular} +%\end{center} \begin{minipage}{6.0cm} \includegraphics[width=5.8cm]{c_sub_si110.ps} \end{minipage} \begin{minipage}{7cm} -\small +\scriptsize \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 Less favorable than C-Si \hkl<1 0 0> dumbbell\\ - ($E_{\text{f}}=3.88\text{ eV}$) + \item Most favorable: \cs{} along \hkl<1 1 0> chain \si{} + \item Less favorable than C-Si \hkl<1 0 0> dumbbell \item Interaction drops quickly to zero\\ - (low interaction capture radius) + $\rightarrow$ 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{itemize} + \item Low migration barrier +\end{itemize} +\end{minipage} +\begin{minipage}{6.5cm} +\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 +} \end{minipage} \end{slide} @@ -1840,6 +1885,66 @@ Only short range order observable\\ \end{slide} +\begin{slide} + + {\large\bf\boldmath + Silicon carbide precipitation simulations at $450\,^{\circ}\mathrm{C}$ as in IBS + } + + \small + +\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} + +\begin{minipage}{6.5cm} +\includegraphics[width=6.4cm]{sic_prec_450_si-c.ps} +\end{minipage} +\begin{minipage}{6.5cm} +\scriptsize +\underline{Low C concentration ($V_1$)}\\ +\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 +\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{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} +\end{itemize} +\end{minipage} + }}} +\end{pspicture} + +\end{slide} + \begin{slide} {\large\bf @@ -1978,6 +2083,85 @@ in c-Si \end{slide} +\begin{slide} + + {\large\bf + Increased temperature simulations at low C concentration + } + +\small + +\begin{minipage}{6.5cm} +\includegraphics[width=6.4cm]{tot_pc_thesis.ps} +\end{minipage} +\begin{minipage}{6.5cm} +\includegraphics[width=6.4cm]{tot_pc3_thesis.ps} +\end{minipage} + +\begin{minipage}{6.5cm} +\includegraphics[width=6.4cm]{tot_pc2_thesis.ps} +\end{minipage} +\begin{minipage}{6.5cm} +\scriptsize + \underline{Si-C bonds:} + \begin{itemize} + \item Vanishing cut-off artifact (above $1650\,^{\circ}\mathrm{C}$) + \item Structural change: C-Si \hkl<1 0 0> $\rightarrow$ C$_{\text{sub}}$ + \end{itemize} + \underline{Si-Si bonds:} + {\color{blue}Si-C$_{\text{sub}}$-Si} along \hkl<1 1 0> + ($\rightarrow$ 0.325 nm)\\[0.1cm] + \underline{C-C bonds:} + \begin{itemize} + \item C-C next neighbour pairs reduced (mandatory) + \item Peak at 0.3 nm slightly shifted + \begin{itemize} + \item C-Si \hkl<1 0 0> combinations (dashed arrows)\\ + $\rightarrow$ C-Si \hkl<1 0 0> \& C$_{\text{sub}}$ + combinations (|)\\ + $\rightarrow$ pure {\color{blue}C$_{\text{sub}}$ combinations} + ($\downarrow$) + \item Range [|-$\downarrow$]: + {\color{blue}C$_{\text{sub}}$ \& C$_{\text{sub}}$ + with nearby Si$_{\text{I}}$} + \end{itemize} + \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} + +\begin{pspicture}(0,0)(0,0) +\rput(6.7,5.2){\rnode{init}{\psframebox[fillstyle=solid,fillcolor=white]{ +\begin{minipage}{10cm} +\small +{\color{blue}\bf Stretched SiC in c-Si} +\begin{itemize} +\item Consistent to precipitation model involving \cs{} +\item Explains annealing behavior of high/low T C implants + \begin{itemize} + \item Low T: highly mobiel \ci{} + \item High T: stable configurations of \cs{} + \end{itemize} +\end{itemize} +$\Rightarrow$ High T $\leftrightarrow$ IBS conditions far from equilibrium\\ +$\Rightarrow$ Precipitation mechanism involving \cs{} +\end{minipage} + }}} +\end{pspicture} + +\end{slide} + \begin{slide} {\large\bf @@ -1993,14 +2177,10 @@ in c-Si \includegraphics[width=6.4cm]{12_pc_c_thesis.ps} \end{minipage} -\begin{center} -Decreasing cut-off artifact\\ -High amount of {\color{red}damage} \& alignement to c-Si host matrix lost -$\Rightarrow$ hard to categorize -\end{center} - \vspace{0.1cm} +\scriptsize + \framebox{ \begin{minipage}[t]{6.0cm} 0.186 nm: Si-C pairs $\uparrow$\\ @@ -2021,16 +2201,28 @@ $\approx$0.35 nm: C-Si-Si \end{minipage} } -\vspace{0.1cm} +\begin{itemize} +\item Decreasing cut-off artifact +\item {\color{red}Amorphous} SiC-like phase remains +\item High amount of {\color{red}damage} \& alignement to c-Si host matrix lost +\item Slightly sharper peaks $\Rightarrow$ indicate slight {\color{blue}acceleration of dynamics} due to temperature +\end{itemize} + +\vspace{-0.1cm} \begin{center} -{\color{red}Amorphous} SiC-like phase remains\\ -Slightly sharper peaks -$\Rightarrow$ indicate slight {\color{blue}acceleration of dynamics} -due to temperature\\[0.1cm] +{\color{blue} \framebox{ -\bf -Actual SiC precipitation not accessible by MD +{\color{black} +High C \& small $V$ \& short $t$ +$\Rightarrow$ +} +Slow restructuring due to strong C-C bonds +{\color{black} +$\Leftarrow$ +High C \& low T implants +} +} } \end{center} @@ -2044,7 +2236,25 @@ Actual SiC precipitation not accessible by MD \scriptsize -\vspace{0.1cm} +%\vspace{0.1cm} + +\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} +\end{minipage} +} + +%\vspace{0.1cm} \framebox{ \begin{minipage}{12.9cm} @@ -2075,23 +2285,11 @@ Actual SiC precipitation not accessible by MD \end{minipage} } -\vspace{0.2cm} - -\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} -\end{minipage} +\begin{center} +{\color{blue} +\framebox{Precipitation by successive agglomeration of \cs{}} } +\end{center} \end{slide} -- 2.39.2