X-Git-Url: https://hackdaworld.org/gitweb/?p=lectures%2Flatex.git;a=blobdiff_plain;f=posic%2Ftalks%2Fmpi_app.tex;h=11274be50f7654cfd1b4f2c3fdb379a5f0545901;hp=fedd211a2bd416d7bfb619bbcb4a5a1411e842ff;hb=b46804e27e8e7ee27ce2981a3664cfa97a8d2556;hpb=6ace91a54c471d1cfe9703253a58ca06d52898bb diff --git a/posic/talks/mpi_app.tex b/posic/talks/mpi_app.tex index fedd211..11274be 100644 --- a/posic/talks/mpi_app.tex +++ b/posic/talks/mpi_app.tex @@ -7,6 +7,7 @@ \usepackage[latin1]{inputenc} \usepackage[T1]{fontenc} \usepackage{amsmath} +\usepackage{stmaryrd} \usepackage{latexsym} \usepackage{ae} @@ -20,6 +21,7 @@ \usepackage{pstricks} \usepackage{pst-node} +\usepackage{pst-grad} %\usepackage{epic} %\usepackage{eepic} @@ -54,6 +56,33 @@ \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=hred,gradend=white,gradlines=1000,gradmidpoint=1,linestyle=none]{ +\begin{minipage}{14cm} +\hfill +\vspace{0.7cm} +\end{minipage} +}} +\end{pspicture} +} + +\newcommand{\headphd}{ +\begin{pspicture}(0,0)(0,0) +\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} +\end{minipage} +}} +\end{pspicture} +} + \begin{document} \extraslideheight{10in} @@ -146,8 +175,6 @@ E\\ % no vertical centering \centerslidesfalse -%\ifnum1=0 - % intro \begin{slide} @@ -403,18 +430,18 @@ 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=solid,fillcolor=white]{ +\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{red}Diploma thesis}\\ +{\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=solid,fillcolor=white]{ +\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{blue}Doctoral studies}\\ +{\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 @@ -432,6 +459,7 @@ Ion beam synthesis (IBS) of burried 3C-SiC layers in Si\hkl(1 0 0) \begin{slide} +\headdiplom {\large\bf Selforganization of nanometric amorphous SiC lamellae } @@ -453,7 +481,8 @@ Ion beam synthesis (IBS) of burried 3C-SiC layers in Si\hkl(1 0 0) \begin{minipage}{12cm} \includegraphics[width=9cm]{../../nlsop/img/k393abild1_e_l.eps}\\ {\scriptsize -XTEM bright-field, \unit[180]{keV} C$^+ \rightarrow$ Si, \degc{150}, +XTEM bright-field, \unit[180]{keV} C$^+ \rightarrow$ Si, +{\color{red}\underline{\degc{150}}}, Dose: \unit[4.3 $\times 10^{17}$]{cm$^{-2}$} } \end{minipage} @@ -473,6 +502,7 @@ XTEM bright-field and respective EFTEM C map \begin{slide} +\headdiplom {\large\bf Model displaying the formation of ordered lamellae } @@ -509,6 +539,7 @@ XTEM bright-field and respective EFTEM C map \begin{slide} +\headdiplom {\large\bf Implementation of the Monte Carlo code } @@ -554,38 +585,46 @@ p_{a \rightarrow c}(\vec r) = (1 - p_{c \rightarrow a}(\vec r)) \Big(1 - \frac{\ \begin{slide} \begin{minipage}{3.7cm} +\begin{pspicture}(0,0)(0,0) +\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} +\end{minipage} +}} +\end{pspicture} {\large\bf Results } \footnotesize -\vspace{1.0cm} +\vspace{1.2cm} Evolution of the \ldots \begin{itemize} \item continuous\\ amorphous layer \item a/c interface - \item lamella precipitates + \item lamellar precipitates \end{itemize} -\ldots reproduced!\\[1.5cm] +\ldots reproduced!\\[1.4cm] {\color{blue} \begin{center} Experiment \& simulation\\ in good agreement\\[1.0cm] -Simulation is able to model the whole depth region\\[1.0cm] +Simulation is able to model the whole depth region\\[1.2cm] \end{center} } \end{minipage} -\begin{minipage}{0.4cm} +\begin{minipage}{0.5cm} \vfill \end{minipage} \begin{minipage}{8.0cm} - \vspace{-0.2cm} + \vspace{-0.3cm} \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} @@ -594,6 +633,7 @@ Simulation is able to model the whole depth region\\[1.0cm] \begin{slide} +\headdiplom {\large\bf Structural \& compositional details } @@ -618,7 +658,7 @@ Simulation is able to model the whole depth region\\[1.0cm] \item C accumulation in the amorphous phase / Origin of stress \end{itemize} -\begin{picture}(0,0)(-265,-30) +\begin{picture}(0,0)(-260,-50) \framebox{ \begin{minipage}{3cm} \begin{center} @@ -634,82 +674,130 @@ by simulation! \end{slide} - -\end{document} - -% continue here -\fi - -\ifnum1=0 - \begin{slide} +\headphd {\large\bf - Model displaying the formation of ordered lamellae + Formation of epitaxial single crystalline 3C-SiC } -\framebox{ - \begin{minipage}{6.3cm} +\footnotesize + +\vspace{0.2cm} + +\begin{center} +\begin{itemize} + \item \underline{Implantation step 1}\\[0.1cm] + Almost stoichiometric dose | \unit[180]{keV} | \degc{500}\\ + $\Rightarrow$ Epitaxial {\color{blue}3C-SiC} layer \& + {\color{blue}precipitates} + \item \underline{Implantation step 2}\\[0.1cm] + Little remaining dose | \unit[180]{keV} | \degc{250}\\ + $\Rightarrow$ + Destruction/Amorphization of precipitates at layer interface + \item \underline{Annealing}\\[0.1cm] + \unit[10]{h} at \degc{1250}\\ + $\Rightarrow$ Homogeneous 3C-SiC layer with sharp interfaces +\end{itemize} +\end{center} + +\begin{minipage}{7cm} +\includegraphics[width=7cm]{ibs_3c-sic.eps} +\end{minipage} +\begin{minipage}{5cm} +\begin{pspicture}(0,0)(0,0) +\rnode{box}{ +\psframebox[fillstyle=solid,fillcolor=white,linecolor=blue,linestyle=solid]{ +\begin{minipage}{5.3cm} \begin{center} {\color{blue} - Precipitation mechanism not yet fully understood! + 3C-SiC precipitation\\ + not yet fully understood } + \end{center} + \vspace*{0.1cm} \renewcommand\labelitemi{$\Rightarrow$} - \small - \underline{Understanding the SiC precipitation} + Details of the SiC precipitation \begin{itemize} - \item significant technological progress in SiC thin film formation - \item perspectives for processes relying upon prevention of SiC precipitation + \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{minipage} +}} +\rput(-6.8,5.4){\pnode{h0}} +\rput(-3.0,5.4){\pnode{h1}} +\ncline[linecolor=blue]{-}{h0}{h1} +\ncline[linecolor=blue]{->}{h1}{box} +\end{pspicture} +\end{minipage} \end{slide} \begin{slide} - {\large\bf +\headphd +{\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 + \framebox{ + \begin{minipage}{3.6cm} + \begin{center} + Si \& SiC lattice structure\\[0.1cm] + \includegraphics[width=2.3cm]{sic_unit_cell.eps} + \end{center} +{\tiny + \begin{minipage}{1.7cm} +\underline{Silicon}\\ +{\color{yellow}$\bullet$} Si | {\color{gray}$\bullet$} Si\\ +$a=\unit[5.429]{\\A}$\\ +$\rho^*_{\text{Si}}=\unit[100]{\%}$ + \end{minipage} + \begin{minipage}{1.7cm} +\underline{Silicon carbide}\\ +{\color{yellow}$\bullet$} Si | {\color{gray}$\bullet$} C\\ +$a=\unit[4.359]{\\A}$\\ +$\rho^*_{\text{Si}}=\unit[97]{\%}$ + \end{minipage} +} \end{minipage} - \hspace{0.6cm} - \begin{minipage}{3.8cm} + } + \hspace{0.1cm} + \begin{minipage}{4.1cm} \begin{center} \includegraphics[width=3.3cm]{tem_c-si-db.eps} \end{center} \end{minipage} - \hspace{0.6cm} - \begin{minipage}{3.8cm} + \hspace{0.1cm} + \begin{minipage}{4.0cm} \begin{center} \includegraphics[width=3.3cm]{tem_3c-sic.eps} \end{center} \end{minipage} - \begin{minipage}{4cm} + \vspace{0.1cm} + + \begin{minipage}{4.0cm} \begin{center} C-Si dimers (dumbbells)\\[-0.1cm] on Si interstitial sites \end{center} \end{minipage} - \hspace{0.2cm} - \begin{minipage}{4.2cm} + \hspace{0.1cm} + \begin{minipage}{4.1cm} \begin{center} Agglomeration of C-Si dumbbells\\[-0.1cm] $\Rightarrow$ dark contrasts \end{center} \end{minipage} - \hspace{0.2cm} - \begin{minipage}{4cm} + \hspace{0.1cm} + \begin{minipage}{4.0cm} \begin{center} Precipitation of 3C-SiC in Si\\[-0.1cm] $\Rightarrow$ Moir\'e fringes\\[-0.1cm] @@ -717,37 +805,39 @@ by simulation! \end{center} \end{minipage} - \begin{minipage}{3.8cm} + \vspace{0.1cm} + + \begin{minipage}{4.0cm} \begin{center} \includegraphics[width=3.3cm]{sic_prec_seq_01.eps} \end{center} \end{minipage} - \hspace{0.6cm} - \begin{minipage}{3.8cm} + \hspace{0.1cm} + \begin{minipage}{4.1cm} \begin{center} \includegraphics[width=3.3cm]{sic_prec_seq_02.eps} \end{center} \end{minipage} - \hspace{0.6cm} - \begin{minipage}{3.8cm} + \hspace{0.1cm} + \begin{minipage}{4.0cm} \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) -\rput(12.7,0.3){\rnode{init}{\psframebox[fillstyle=solid,fillcolor=hb]{ +\psline[linewidth=2pt]{->}(8.3,2)(8.8,2) +\psellipse[linecolor=blue](11.1,6.0)(0.3,0.5) +\rput{-20}{\psellipse[linecolor=blue](3.1,8.2)(0.3,0.5)} +\psline[linewidth=2pt]{->}(3.9,2)(4.4,2) +\rput(11.8,0.3){\rnode{init}{\psframebox[fillstyle=solid,fillcolor=hb]{ $4a_{\text{Si}}=5a_{\text{SiC}}$ }}} -\rput(12.2,8){\rnode{init}{\psframebox[fillstyle=solid,fillcolor=hb]{ +\rput(11.5,8){\rnode{init}{\psframebox[fillstyle=solid,fillcolor=hb]{ \hkl(h k l) planes match }}} -\rput(9.7,6.2){\rnode{init}{\psframebox[fillstyle=solid,fillcolor=hb]{ -r = 2 - 4 nm +\rput(8.5,6.2){\rnode{init}{\psframebox[fillstyle=solid,fillcolor=hb]{ +r = \unit[2--4]{nm} }}} \end{pspicture} @@ -755,47 +845,67 @@ r = 2 - 4 nm \begin{slide} - {\large\bf - Supposed precipitation mechanism of SiC in Si - } +\headphd +{\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 + \framebox{ + \begin{minipage}{3.6cm} + \begin{center} + Si \& SiC lattice structure\\[0.1cm] + \includegraphics[width=2.3cm]{sic_unit_cell.eps} + \end{center} +{\tiny + \begin{minipage}{1.7cm} +\underline{Silicon}\\ +{\color{yellow}$\bullet$} Si | {\color{gray}$\bullet$} Si\\ +$a=\unit[5.429]{\\A}$\\ +$\rho^*_{\text{Si}}=\unit[100]{\%}$ + \end{minipage} + \begin{minipage}{1.7cm} +\underline{Silicon carbide}\\ +{\color{yellow}$\bullet$} Si | {\color{gray}$\bullet$} C\\ +$a=\unit[4.359]{\\A}$\\ +$\rho^*_{\text{Si}}=\unit[97]{\%}$ + \end{minipage} +} \end{minipage} - \hspace{0.6cm} - \begin{minipage}{3.8cm} + } + \hspace{0.1cm} + \begin{minipage}{4.1cm} \begin{center} \includegraphics[width=3.3cm]{tem_c-si-db.eps} \end{center} \end{minipage} - \hspace{0.6cm} - \begin{minipage}{3.8cm} + \hspace{0.1cm} + \begin{minipage}{4.0cm} \begin{center} \includegraphics[width=3.3cm]{tem_3c-sic.eps} \end{center} \end{minipage} - \begin{minipage}{4cm} + \vspace{0.1cm} + + \begin{minipage}{4.0cm} \begin{center} C-Si dimers (dumbbells)\\[-0.1cm] on Si interstitial sites \end{center} \end{minipage} - \hspace{0.2cm} - \begin{minipage}{4.2cm} + \hspace{0.1cm} + \begin{minipage}{4.1cm} \begin{center} Agglomeration of C-Si dumbbells\\[-0.1cm] $\Rightarrow$ dark contrasts \end{center} \end{minipage} - \hspace{0.2cm} - \begin{minipage}{4cm} + \hspace{0.1cm} + \begin{minipage}{4.0cm} \begin{center} Precipitation of 3C-SiC in Si\\[-0.1cm] $\Rightarrow$ Moir\'e fringes\\[-0.1cm] @@ -803,60 +913,81 @@ r = 2 - 4 nm \end{center} \end{minipage} - \begin{minipage}{3.8cm} + \vspace{0.1cm} + + \begin{minipage}{4.0cm} \begin{center} \includegraphics[width=3.3cm]{sic_prec_seq_01.eps} \end{center} \end{minipage} - \hspace{0.6cm} - \begin{minipage}{3.8cm} + \hspace{0.1cm} + \begin{minipage}{4.1cm} \begin{center} \includegraphics[width=3.3cm]{sic_prec_seq_02.eps} \end{center} \end{minipage} - \hspace{0.6cm} - \begin{minipage}{3.8cm} + \hspace{0.1cm} + \begin{minipage}{4.0cm} \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) -\rput(12.7,0.3){\rnode{init}{\psframebox[fillstyle=solid,fillcolor=hb]{ +\psline[linewidth=2pt]{->}(8.3,2)(8.8,2) +\psellipse[linecolor=blue](11.1,6.0)(0.3,0.5) +\rput{-20}{\psellipse[linecolor=blue](3.1,8.2)(0.3,0.5)} +\psline[linewidth=2pt]{->}(3.9,2)(4.4,2) +\rput(11.8,0.3){\rnode{init}{\psframebox[fillstyle=solid,fillcolor=hb]{ $4a_{\text{Si}}=5a_{\text{SiC}}$ }}} -\rput(12.2,8){\rnode{init}{\psframebox[fillstyle=solid,fillcolor=hb]{ +\rput(11.5,8){\rnode{init}{\psframebox[fillstyle=solid,fillcolor=hb]{ \hkl(h k l) planes match }}} -\rput(9.7,6.2){\rnode{init}{\psframebox[fillstyle=solid,fillcolor=hb]{ -r = 2 - 4 nm +\rput(8.5,6.2){\rnode{init}{\psframebox[fillstyle=solid,fillcolor=hb]{ +r = \unit[2--4]{nm} }}} -\rput(6.7,5.2){\rnode{init}{\psframebox[fillstyle=solid,fillcolor=white]{ +% controversial view! +\rput(6.5,5.0){\psframebox[fillstyle=solid,opacity=0.5,fillcolor=black]{ +\begin{minipage}{14cm} +\hfill +\vspace{12cm} +\end{minipage} +}} +\rput(6.5,5.3){\rnode{init}{\psframebox[fillstyle=solid,fillcolor=white,linewidth=0.1cm]{ \begin{minipage}{10cm} \small -{\color{red}\bf Controversial views} +\vspace*{0.2cm} +\begin{center} +{\color{gray}\bf Controversial findings} +\end{center} \begin{itemize} -\item Implantations at high T (Nejim et al.) +\item High-temperature implantation {\tiny\color{gray}/Nejim~et~al./} \begin{itemize} - \item Topotactic transformation based on \cs - \item \si{} as supply reacting with further C in cleared volume + \item C incorporated {\color{blue}substitutionally} on regular Si lattice sites + \item \si{} reacting with further C in cleared volume \end{itemize} -\item Annealing behavior (Serre et al.) +\item Annealing behavior {\tiny\color{gray}/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) + \item Room temperature implantation $\rightarrow$ high C diffusion + \item Elevated temperature implantation $\rightarrow$ no C redistribution \end{itemize} + $\Rightarrow$ mobile {\color{red}\ci} opposed to + stable {\color{blue}\cs{}} configurations \item Strained silicon \& Si/SiC heterostructures + {\tiny\color{gray}/Strane~et~al./Guedj~et~al./} \begin{itemize} - \item Coherent SiC precipitates (tensile strain) + \item {\color{blue}Coherent} SiC precipitates (tensile strain) \item Incoherent SiC (strain relaxation) \end{itemize} \end{itemize} +\vspace{0.1cm} +\begin{center} +{\Huge${\lightning}$} \hspace{0.3cm} +{\color{blue}\cs{}} --- vs --- {\color{red}\ci} \hspace{0.3cm} +{\Huge${\lightning}$} +\end{center} +\vspace{0.2cm} \end{minipage} }}} \end{pspicture} @@ -865,160 +996,110 @@ r = 2 - 4 nm \begin{slide} - {\large\bf - Molecular dynamics (MD) simulations - } - - \vspace{12pt} +\headphd +{\large\bf + Utilized computational methods +} - \small +\vspace{0.3cm} - {\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 Erhart/Albe potential: Tersoff-like bond order potential - \vspace*{12pt} - \[ - E = \frac{1}{2} \sum_{i \neq j} \pot_{ij}, \quad - \pot_{ij} = {\color{red}f_C(r_{ij})} - \left[ f_R(r_{ij}) + {\color{blue}b_{ij}} f_A(r_{ij}) \right] - \] - \end{itemize} +\small - \begin{picture}(0,0)(-230,-30) - \includegraphics[width=5cm]{tersoff_angle.eps} - \end{picture} - -\end{slide} +{\bf Molecular dynamics (MD)}\\[0.1cm] +\scriptsize +\begin{tabular}{| p{4.5cm} | p{7.5cm} |} +\hline +System of $N$ particles & +$N=5832\pm 1$ (Defects), $N=238328+6000$ (Precipitation)\\ +Phase space propagation & +Velocity Verlet | timestep: \unit[1]{fs} \\ +Analytical interaction potential & +Tersoff-like {\color{red}short-range}, {\color{blue}bond order} potential +(Erhart/Albe) +$\displaystyle +E = \frac{1}{2} \sum_{i \neq j} \pot_{ij}, \quad + \pot_{ij} = {\color{red}f_C(r_{ij})} + \left[ f_R(r_{ij}) + {\color{blue}b_{ij}} f_A(r_{ij}) \right] +$\\ +Observables: time/ensemble averages & +NpT (isothermal-isobaric) | Berendsen thermostat/barostat\\ +\hline +\end{tabular} -\begin{slide} +\small - {\large\bf - Density functional theory (DFT) calculations - } +\vspace{0.3cm} - \small +{\bf Density functional theory (DFT)} - Basic ingredients necessary for DFT +\scriptsize - \begin{itemize} - \item \underline{Hohenberg-Kohn theorem} - ground state density $n_0(r)$ ... - \begin{itemize} - \item ... uniquely determines the ground state potential - / wavefunctions - \item ... minimizes the systems total energy - \end{itemize} - \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}(3.5,-2.0){2.5}{130}{15} +\psarcn[linewidth=0.07cm,linestyle=dashed]{->}(3.5,-2.0){2.5}{230}{165} +\psarcn[linewidth=0.07cm,linestyle=dashed]{->}(3.5,-2.0){2.5}{345}{310} -\begin{pspicture}(0,0)(0,0) -\psellipse[linecolor=blue](1.5,6.75)(0.5,0.3) \end{pspicture} +\end{minipage} \end{slide} \begin{slide} +\headphd {\large\bf - C and Si self-interstitial point defects in silicon + Point defects \& defect migration } \small - \vspace*{0.3cm} + \vspace{0.2cm} -\begin{minipage}{8cm} -Procedure:\\[0.3cm] - \begin{pspicture}(0,0)(7,5) - \rput(3.5,4){\rnode{init}{\psframebox[fillstyle=solid,fillcolor=hb]{ +\begin{minipage}[b]{7.5cm} +{\bf Defect structure}\\ + \begin{pspicture}(0,0)(7,4.4) + \rput(3.5,3.2){\rnode{init}{\psframebox[fillstyle=solid,fillcolor=hb]{ \parbox{7cm}{ \begin{itemize} \item Creation of c-Si simulation volume @@ -1026,13 +1107,13 @@ Procedure:\\[0.3cm] \item $T=0\text{ K}$, $p=0\text{ bar}$ \end{itemize} }}}} -\rput(3.5,2.1){\rnode{insert}{\psframebox{ +\rput(3.5,1.3){\rnode{insert}{\psframebox{ \parbox{7cm}{ \begin{center} Insertion of interstitial C/Si atoms \end{center} }}}} - \rput(3.5,1){\rnode{cool}{\psframebox[fillstyle=solid,fillcolor=lbb]{ + \rput(3.5,0.2){\rnode{cool}{\psframebox[fillstyle=solid,fillcolor=lbb]{ \parbox{7cm}{ \begin{center} Relaxation / structural energy minimization @@ -1042,58 +1123,104 @@ Procedure:\\[0.3cm] \ncline[]{->}{insert}{cool} \end{pspicture} \end{minipage} -\begin{minipage}{5cm} - \includegraphics[width=5cm]{unit_cell_e.eps}\\ +\begin{minipage}[b]{4.5cm} +\begin{center} +\includegraphics[width=3.8cm]{unit_cell_e.eps}\\ +\end{center} +\begin{minipage}{2.21cm} +{\scriptsize +{\color{red}$\bullet$} Tetrahedral\\[-0.1cm] +{\color{green}$\bullet$} Hexagonal\\[-0.1cm] +{\color{yellow}$\bullet$} \hkl<1 0 0> DB +} +\end{minipage} +\begin{minipage}{2.21cm} +{\scriptsize +{\color{magenta}$\bullet$} \hkl<1 1 0> DB\\[-0.1cm] +{\color{cyan}$\bullet$} Bond-centered\\[-0.1cm] +{\color{black}$\bullet$} Vac. / Sub. +} +\end{minipage} \end{minipage} -\begin{minipage}{9cm} - \begin{tabular}{l c c} - \hline - & size [unit cells] & \# atoms\\ -\hline -VASP & $3\times 3\times 3$ & $216\pm 1$ \\ -Erhart/Albe & $9\times 9\times 9$ & $5832\pm 1$\\ -\hline - \end{tabular} +\vspace{0.2cm} + +\begin{minipage}[b]{6cm} +{\bf Defect formation energy}\\ +\framebox{ +$E_{\text{f}}=E-\sum_i N_i\mu_i$}\\[0.1cm] +Particle reservoir: Si \& SiC\\[0.2cm] +{\bf Binding energy}\\ +\framebox{ +$ +E_{\text{b}}= +E_{\text{f}}^{\text{comb}}- +E_{\text{f}}^{1^{\text{st}}}- +E_{\text{f}}^{2^{\text{nd}}} +$ +}\\[0.1cm] +\footnotesize +$E_{\text{b}}<0$: energetically favorable configuration\\ +$E_{\text{b}}\rightarrow 0$: non-interacting, isolated defects\\ \end{minipage} -\begin{minipage}{4cm} -{\color{red}$\bullet$} Tetrahedral\\ -{\color{green}$\bullet$} Hexagonal\\ -{\color{yellow}$\bullet$} \hkl<1 0 0> dumbbell\\ -{\color{magenta}$\bullet$} \hkl<1 1 0> dumbbell\\ -{\color{cyan}$\bullet$} Bond-centered\\ -{\color{black}$\bullet$} Vacancy / Substitutional +\begin{minipage}[b]{6cm} +{\bf Migration barrier} +\footnotesize +\begin{itemize} + \item Displace diffusing atom + \item Constrain relaxation of (diffusing) atoms + \item Record configurational energy +\end{itemize} +\begin{picture}(0,0)(-60,-33) +\includegraphics[width=4.5cm]{crt_mod.eps} +\end{picture} \end{minipage} \end{slide} \begin{slide} - \footnotesize - -\begin{minipage}{9.5cm} +\footnotesize - {\large\bf - Si self-interstitial point defects in silicon\\ - } +\headphd +{\large\bf + Si self-interstitial point defects in silicon\\[0.1cm] +} +\begin{center} \begin{tabular}{l c c c c c} \hline $E_{\text{f}}$ [eV] & \hkl<1 1 0> DB & H & T & \hkl<1 0 0> DB & V \\ \hline - VASP & \underline{3.39} & 3.42 & 3.77 & 4.41 & 3.63 \\ + \textsc{vasp} & \underline{3.39} & 3.42 & 3.77 & 4.41 & 3.63 \\ Erhart/Albe & 4.39 & 4.48$^*$ & \underline{3.40} & 5.42 & 3.13 \\ \hline -\end{tabular}\\[0.2cm] +\end{tabular}\\[0.4cm] +\end{center} -\begin{minipage}{4.7cm} -\includegraphics[width=4.7cm]{e_kin_si_hex.ps} +\begin{minipage}{3cm} +\begin{center} +\underline{Vacancy}\\ +\includegraphics[width=2.8cm]{si_pd_albe/vac.eps} +\end{center} \end{minipage} -\begin{minipage}{4.7cm} +\begin{minipage}{3cm} \begin{center} -{\tiny nearly T $\rightarrow$ T}\\ +\underline{\hkl<1 1 0> DB}\\ +\includegraphics[width=2.8cm]{si_pd_albe/110_bonds.eps} +\end{center} +\end{minipage} +\begin{minipage}{3cm} +\begin{center} +\underline{\hkl<1 0 0> DB}\\ +\includegraphics[width=2.8cm]{si_pd_albe/100_bonds.eps} +\end{center} +\end{minipage} +\begin{minipage}{3cm} +\begin{center} +\underline{Tetrahedral}\\ +\includegraphics[width=2.8cm]{si_pd_albe/tet_bonds.eps} \end{center} -\includegraphics[width=4.7cm]{nhex_tet.ps} \end{minipage}\\ \underline{Hexagonal} \hspace{2pt} @@ -1101,7 +1228,7 @@ Erhart/Albe & $9\times 9\times 9$ & $5832\pm 1$\\ \framebox{ \begin{minipage}{2.7cm} $E_{\text{f}}^*=4.48\text{ eV}$\\ -\includegraphics[width=2.7cm]{si_pd_albe/hex_a.eps} +\includegraphics[width=2.7cm]{si_pd_albe/hex_a_bonds.eps} \end{minipage} \begin{minipage}{0.4cm} \begin{center} @@ -1110,28 +1237,14 @@ $\Rightarrow$ \end{minipage} \begin{minipage}{2.7cm} $E_{\text{f}}=3.96\text{ eV}$\\ -\includegraphics[width=2.8cm]{si_pd_albe/hex.eps} +\includegraphics[width=2.8cm]{si_pd_albe/hex_bonds.eps} \end{minipage} } -\begin{minipage}{2.9cm} -\begin{flushright} -\underline{Vacancy}\\ -\includegraphics[width=3.0cm]{si_pd_albe/vac.eps} -\end{flushright} -\end{minipage} - -\end{minipage} -\begin{minipage}{3.5cm} - -\begin{flushright} -\underline{\hkl<1 1 0> dumbbell}\\ -\includegraphics[width=3.0cm]{si_pd_albe/110.eps}\\ -\underline{Tetrahedral}\\ -\includegraphics[width=3.0cm]{si_pd_albe/tet.eps}\\ -\underline{\hkl<1 0 0> dumbbell}\\ -\includegraphics[width=3.0cm]{si_pd_albe/100.eps} -\end{flushright} - +\begin{minipage}{5.5cm} +\begin{center} +{\tiny nearly T $\rightarrow$ T}\\ +\end{center} +\includegraphics[width=6.0cm]{nhex_tet.ps} \end{minipage} \end{slide} @@ -1140,71 +1253,73 @@ $E_{\text{f}}=3.96\text{ eV}$\\ \footnotesize - {\large\bf - C interstitial point defects in silicon\\[-0.1cm] - } +\headphd +{\large\bf + C interstitial point defects in silicon\\ +} \begin{tabular}{l c c c c c c r} \hline - $E_{\text{f}}$ & T & H & \hkl<1 0 0> DB & \hkl<1 1 0> DB & S & B & \cs{} \& \si\\ + $E_{\text{f}}$ [eV] & T & H & \hkl<1 0 0> DB & \hkl<1 1 0> DB & S & B & + {\color{black} \cs{} \& \si}\\ \hline - VASP & unstable & unstable & \underline{3.72} & 4.16 & 1.95 & 4.66 & {\color{green}4.17}\\ - Erhart/Albe MD & 6.09 & 9.05$^*$ & \underline{3.88} & 5.18 & {\color{red}0.75} & 5.59$^*$ & {\color{green}4.43} \\ + \textsc{vasp} & unstable & unstable & \underline{3.72} & 4.16 & 1.95 & 4.66 & {\color{green}4.17}\\ + Erhart/Albe & 6.09 & 9.05$^*$ & \underline{3.88} & 5.18 & {\color{red}0.75} & 5.59$^*$ & {\color{green}4.43} \\ \hline \end{tabular}\\[0.1cm] \framebox{ -\begin{minipage}{2.7cm} +\begin{minipage}{2.8cm} \underline{Hexagonal} \hspace{2pt} \href{../video/c_in_si_int_hexa.avi}{$\rhd$}\\ $E_{\text{f}}^*=9.05\text{ eV}$\\ -\includegraphics[width=2.7cm]{c_pd_albe/hex.eps} +\includegraphics[width=2.8cm]{c_pd_albe/hex_bonds.eps} \end{minipage} \begin{minipage}{0.4cm} \begin{center} $\Rightarrow$ \end{center} \end{minipage} -\begin{minipage}{2.7cm} +\begin{minipage}{2.8cm} \underline{\hkl<1 0 0>}\\ $E_{\text{f}}=3.88\text{ eV}$\\ -\includegraphics[width=2.7cm]{c_pd_albe/100.eps} +\includegraphics[width=2.8cm]{c_pd_albe/100_bonds.eps} \end{minipage} } -\begin{minipage}{2cm} +\begin{minipage}{1.4cm} \hfill \end{minipage} -\begin{minipage}{3cm} +\begin{minipage}{3.0cm} \begin{flushright} \underline{Tetrahedral}\\ -\includegraphics[width=3.0cm]{c_pd_albe/tet.eps} +\includegraphics[width=3.0cm]{c_pd_albe/tet_bonds.eps} \end{flushright} \end{minipage} \framebox{ -\begin{minipage}{2.7cm} +\begin{minipage}{2.8cm} \underline{Bond-centered}\\ $E_{\text{f}}^*=5.59\text{ eV}$\\ -\includegraphics[width=2.7cm]{c_pd_albe/bc.eps} +\includegraphics[width=2.8cm]{c_pd_albe/bc_bonds.eps} \end{minipage} \begin{minipage}{0.4cm} \begin{center} $\Rightarrow$ \end{center} \end{minipage} -\begin{minipage}{2.7cm} +\begin{minipage}{2.8cm} \underline{\hkl<1 1 0> dumbbell}\\ $E_{\text{f}}=5.18\text{ eV}$\\ -\includegraphics[width=2.7cm]{c_pd_albe/110.eps} +\includegraphics[width=2.8cm]{c_pd_albe/110_bonds.eps} \end{minipage} } -\begin{minipage}{2cm} +\begin{minipage}{1.4cm} \hfill \end{minipage} -\begin{minipage}{3cm} +\begin{minipage}{3.0cm} \begin{flushright} \underline{Substitutional}\\ -\includegraphics[width=3.0cm]{c_pd_albe/sub.eps} +\includegraphics[width=3.0cm]{c_pd_albe/sub_bonds.eps} \end{flushright} \end{minipage} @@ -1212,82 +1327,46 @@ $E_{\text{f}}=5.18\text{ eV}$\\ \begin{slide} +\headphd +{\large\bf\boldmath + C-Si dimer \& bond-centered interstitial configuration +} + \footnotesize - {\large\bf\boldmath - C \hkl<1 0 0> dumbbell interstitial configuration\\ - } +\vspace{0.1cm} -{\tiny -\begin{tabular}{l c c c c c c c c} -\hline - Distances [nm] & $r(1C)$ & $r(2C)$ & $r(3C)$ & $r(12)$ & $r(13)$ & $r(34)$ & $r(23)$ & $r(25)$ \\ -\hline -Erhart/Albe & 0.175 & 0.329 & 0.186 & 0.226 & 0.300 & 0.343 & 0.423 & 0.425 \\ -VASP & 0.174 & 0.341 & 0.182 & 0.229 & 0.286 & 0.347 & 0.422 & 0.417 \\ -\hline -\end{tabular}\\[0.2cm] -\begin{tabular}{l c c c c } -\hline - Angles [$^{\circ}$] & $\theta_1$ & $\theta_2$ & $\theta_3$ & $\theta_4$ \\ -\hline -Erhart/Albe & 140.2 & 109.9 & 134.4 & 112.8 \\ -VASP & 130.7 & 114.4 & 146.0 & 107.0 \\ -\hline -\end{tabular}\\[0.2cm] -\begin{tabular}{l c c c} -\hline - Displacements [nm]& $a$ & $b$ & $|a|+|b|$ \\ -\hline -Erhart/Albe & 0.084 & -0.091 & 0.175 \\ -VASP & 0.109 & -0.065 & 0.174 \\ -\hline -\end{tabular}\\[0.6cm] -} - -\begin{minipage}{3.0cm} +\begin{minipage}[t]{4.1cm} +{\bf\boldmath C \hkl<1 0 0> DB interstitial}\\[0.1cm] +\begin{minipage}{2.0cm} \begin{center} \underline{Erhart/Albe} -\includegraphics[width=3.0cm]{c_pd_albe/100_cmp.eps} +\includegraphics[width=2.0cm]{c_pd_albe/100_cmp.eps} \end{center} \end{minipage} -\begin{minipage}{3.0cm} +\begin{minipage}{2.0cm} \begin{center} -\underline{VASP} -\includegraphics[width=3.0cm]{c_pd_vasp/100_cmp.eps} +\underline{\textsc{vasp}} +\includegraphics[width=2.0cm]{c_pd_vasp/100_cmp.eps} +\end{center} +\end{minipage}\\[0.2cm] +Si-C-Si bond angle $\rightarrow$ \unit[180]{$^{\circ}$}\\ +$\Rightarrow$ $sp$ hybridization\\[0.1cm] +Si-Si-Si bond angle $\rightarrow$ \unit[120]{$^{\circ}$}\\ +$\Rightarrow$ $sp^2$ hybridization +\begin{center} +\includegraphics[width=3.4cm]{c_pd_vasp/eden.eps}\\[-0.1cm] +{\tiny Charge density isosurface} \end{center} -\end{minipage}\\ - -\begin{picture}(0,0)(-185,10) -\includegraphics[width=6.8cm]{100-c-si-db_cmp.eps} -\end{picture} -\begin{picture}(0,0)(-280,-150) -\includegraphics[width=3.3cm]{c_pd_vasp/eden.eps} -\end{picture} - -\begin{pspicture}(0,0)(0,0) -\psellipse[linecolor=green](5.18,5.92)(0.5,0.3) -\psellipse[linecolor=red](3.45,5.92)(1.0,0.4) -\psellipse[linecolor=blue](2.7,6.92)(0.9,0.2) -\psellipse[linecolor=blue](4.65,6.92)(0.9,0.2) -\end{pspicture} - -\end{slide} - -\begin{slide} - -\small - -\begin{minipage}{8.5cm} - - {\large\bf - Bond-centered interstitial configuration\\[-0.1cm] - } - -\begin{minipage}{3.0cm} -\includegraphics[width=2.8cm]{c_pd_vasp/bc_2333.eps}\\ \end{minipage} -\begin{minipage}{5.2cm} +\begin{minipage}{0.2cm} +\hfill +\end{minipage} +\begin{minipage}[t]{8.1cm} +\begin{flushright} +{\bf Bond-centered interstitial}\\[0.1cm] +\begin{minipage}{4.4cm} +%\scriptsize \begin{itemize} \item Linear Si-C-Si bond \item Si: one C \& 3 Si neighbours @@ -1296,6 +1375,11 @@ VASP & 0.109 & -0.065 & 0.174 \\ Real local minimum! \end{itemize} \end{minipage} +\begin{minipage}{2.7cm} +%\includegraphics[width=2.8cm]{c_pd_vasp/bc_2333.eps}\\ +\vspace{0.2cm} +\includegraphics[width=2.8cm]{c_pd_albe/bc_bonds.eps}\\ +\end{minipage} \framebox{ \tiny @@ -1351,716 +1435,544 @@ VASP & 0.109 & -0.065 & 0.174 \\ \end{flushright} \end{minipage} \end{minipage} -}\\[0.1cm] +}\\[0.4cm] -\framebox{ -\begin{minipage}{4.5cm} -\includegraphics[width=4cm]{c_100_mig_vasp/im_spin_diff.eps} -\end{minipage} -\begin{minipage}{3.5cm} +%\framebox{ +\begin{minipage}{3.0cm} +%\scriptsize +\underline{Charge density}\\ {\color{gray}$\bullet$} Spin up\\ {\color{green}$\bullet$} Spin down\\ {\color{blue}$\bullet$} Resulting spin up\\ {\color{yellow}$\bullet$} Si atoms\\ {\color{red}$\bullet$} C atom \end{minipage} -} - +\begin{minipage}{3.6cm} +\includegraphics[width=3.8cm]{c_100_mig_vasp/im_spin_diff.eps} \end{minipage} -\begin{minipage}{4.2cm} -\begin{flushright} -\includegraphics[width=4.3cm]{c_pd_vasp/bc_2333_ksl.ps}\\ -{\color{green}$\Box$} {\tiny unoccupied}\\ -{\color{red}$\bullet$} {\tiny occupied} +%} + \end{flushright} + \end{minipage} +\begin{pspicture}(0,0)(0,0) +\psline[linecolor=gray,linewidth=0.05cm](-7.8,-8.7)(-7.8,0) +\end{pspicture} \end{slide} \begin{slide} - {\large\bf\boldmath - Migration of the C \hkl<1 0 0> dumbbell interstitial - } +\headphd +{\large\bf\boldmath + C interstitial migration --- ab initio +} \scriptsize - {\small Investigated pathways} +\vspace{0.1cm} -\begin{minipage}{8.5cm} -\begin{minipage}{8.3cm} -\underline{\hkl<0 0 -1> $\rightarrow$ \hkl<0 0 1>}\\ -\begin{minipage}{2.4cm} -\includegraphics[width=2.4cm]{c_pd_vasp/100_2333.eps} -\end{minipage} -\begin{minipage}{0.4cm} -$\rightarrow$ -\end{minipage} -\begin{minipage}{2.4cm} -\includegraphics[width=2.4cm]{c_pd_vasp/bc_2333.eps} +\begin{minipage}{6.8cm} +\framebox{\hkl[0 0 -1] $\rightarrow$ \hkl[0 0 1]}\\ +\begin{minipage}{2.0cm} +\includegraphics[width=2.0cm]{c_pd_vasp/100_2333.eps} \end{minipage} -\begin{minipage}{0.4cm} -$\rightarrow$ -\end{minipage} -\begin{minipage}{2.4cm} -\includegraphics[width=2.4cm]{c_pd_vasp/100_next_2333.eps} -\end{minipage} -\end{minipage}\\ -\begin{minipage}{8.3cm} -\underline{\hkl<0 0 -1> $\rightarrow$ \hkl<0 -1 0>}\\ -\begin{minipage}{2.4cm} -\includegraphics[width=2.4cm]{c_pd_vasp/100_2333.eps} -\end{minipage} -\begin{minipage}{0.4cm} +\begin{minipage}{0.2cm} $\rightarrow$ \end{minipage} -\begin{minipage}{2.4cm} -\includegraphics[width=2.4cm]{c_pd_vasp/00-1-0-10_2333.eps} +\begin{minipage}{2.0cm} +\includegraphics[width=2.0cm]{c_pd_vasp/bc_2333.eps} \end{minipage} -\begin{minipage}{0.4cm} +\begin{minipage}{0.2cm} $\rightarrow$ \end{minipage} -\begin{minipage}{2.4cm} -\includegraphics[width=2.4cm]{c_pd_vasp/0-10_2333.eps} -\end{minipage} -\end{minipage}\\ -\begin{minipage}{8.3cm} -\underline{\hkl<0 0 -1> $\rightarrow$ \hkl<0 -1 0> (in place)}\\ -\begin{minipage}{2.4cm} -\includegraphics[width=2.4cm]{c_pd_vasp/100_2333.eps} +\begin{minipage}{2.0cm} +\includegraphics[width=2.0cm]{c_pd_vasp/100_next_2333.eps} +\end{minipage}\\[0.1cm] +Spin polarization\\ +$\Rightarrow$ BC configuration constitutes local minimum\\ +$\Rightarrow$ Migration barrier to reach BC | $\Delta E=\unit[1.2]{eV}$ +\end{minipage} +\begin{minipage}{5.4cm} +\includegraphics[width=6.0cm]{im_00-1_nosym_sp_fullct_thesis_vasp_s.ps} +\end{minipage}\\[0.2cm] +%\hrule +% +\begin{minipage}{6.8cm} +\framebox{\hkl[0 0 -1] $\rightarrow$ \hkl[0 -1 0]}\\ +\begin{minipage}{2.0cm} +\includegraphics[width=2.0cm]{c_pd_vasp/100_2333.eps} \end{minipage} -\begin{minipage}{0.4cm} +\begin{minipage}{0.2cm} $\rightarrow$ \end{minipage} -\begin{minipage}{2.4cm} -\includegraphics[width=2.4cm]{c_pd_vasp/00-1_ip0-10_2333.eps} +\begin{minipage}{2.0cm} +\includegraphics[width=2.0cm]{c_pd_vasp/00-1-0-10_2333.eps} \end{minipage} -\begin{minipage}{0.4cm} +\begin{minipage}{0.2cm} $\rightarrow$ \end{minipage} -\begin{minipage}{2.4cm} -\includegraphics[width=2.4cm]{c_pd_vasp/0-10_ip_2333.eps} -\end{minipage} -\end{minipage} +\begin{minipage}{2.0cm} +\includegraphics[width=2.0cm]{c_pd_vasp/0-10_2333.eps} +\end{minipage}\\[0.1cm] +$\Delta E=\unit[0.9]{eV}$ | Experimental values: \unit[0.70--0.87]{eV}\\ +$\Rightarrow$ {\color{red}Migration mechanism identified!}\\ +Note: Change in orientation \end{minipage} -\framebox{ -\begin{minipage}{4.2cm} - {\small Constrained relaxation\\ - technique (CRT) method}\\ -\includegraphics[width=4cm]{crt_orig.eps} -\begin{itemize} - \item Constrain diffusing atom - \item Static constraints -\end{itemize} -\vspace*{0.3cm} - {\small Modifications}\\ -\includegraphics[width=4cm]{crt_mod.eps} -\begin{itemize} - \item Constrain all atoms - \item Update individual\\ - constraints -\end{itemize} -\end{minipage} -} - -\end{slide} - -\begin{slide} - - {\large\bf\boldmath - Migration of the C \hkl<1 0 0> dumbbell interstitial - } - -\scriptsize - -\framebox{ -\begin{minipage}{5.9cm} -\begin{flushleft} -\includegraphics[width=5.8cm]{im_00-1_nosym_sp_fullct_thesis.ps}\\[0.45cm] -\end{flushleft} -\begin{center} -\begin{picture}(0,0)(60,0) -\includegraphics[width=1cm]{vasp_mig/00-1.eps} -\end{picture} -\begin{picture}(0,0)(-5,0) -\includegraphics[width=1cm]{vasp_mig/bc_00-1_sp.eps} -\end{picture} -\begin{picture}(0,0)(-55,0) -\includegraphics[width=1cm]{vasp_mig/bc.eps} -\end{picture} -\begin{picture}(0,0)(12.5,10) -\includegraphics[width=1cm]{110_arrow.eps} -\end{picture} -\begin{picture}(0,0)(90,0) -\includegraphics[height=0.9cm]{001_arrow.eps} -\end{picture} -\end{center} -\vspace*{0.35cm} -\end{minipage} -} -\begin{minipage}{0.3cm} -\hfill -\end{minipage} -\framebox{ -\begin{minipage}{5.9cm} -\begin{flushright} -\includegraphics[width=5.9cm]{vasp_mig/00-1_0-10_nosym_sp_fullct.ps}\\[0.5cm] -\end{flushright} -\begin{center} -\begin{picture}(0,0)(60,0) -\includegraphics[width=1cm]{vasp_mig/00-1_a.eps} -\end{picture} -\begin{picture}(0,0)(5,0) -\includegraphics[width=1cm]{vasp_mig/00-1_0-10_sp.eps} -\end{picture} -\begin{picture}(0,0)(-55,0) -\includegraphics[width=1cm]{vasp_mig/0-10.eps} -\end{picture} -\begin{picture}(0,0)(12.5,10) -\includegraphics[width=1cm]{100_arrow.eps} -\end{picture} -\begin{picture}(0,0)(90,0) -\includegraphics[height=0.9cm]{001_arrow.eps} -\end{picture} -\end{center} -\vspace*{0.3cm} -\end{minipage}\\ -} - -\vspace*{0.05cm} - -\framebox{ -\begin{minipage}{5.9cm} -\begin{flushleft} -\includegraphics[width=5.9cm]{vasp_mig/00-1_ip0-10_nosym_sp_fullct.ps}\\[0.6cm] -\end{flushleft} +\begin{minipage}{5.4cm} +\includegraphics[width=6.0cm]{00-1_0-10_vasp_s.ps} +\end{minipage}\\[0.1cm] +% \begin{center} -\begin{picture}(0,0)(60,0) -\includegraphics[width=0.9cm]{vasp_mig/00-1_b.eps} -\end{picture} -\begin{picture}(0,0)(10,0) -\includegraphics[width=0.9cm]{vasp_mig/00-1_ip0-10_sp.eps} -\end{picture} -\begin{picture}(0,0)(-60,0) -\includegraphics[width=0.9cm]{vasp_mig/0-10_b.eps} -\end{picture} -\begin{picture}(0,0)(12.5,10) -\includegraphics[width=1cm]{100_arrow.eps} -\end{picture} -\begin{picture}(0,0)(90,0) -\includegraphics[height=0.9cm]{001_arrow.eps} -\end{picture} +Reorientation pathway composed of two consecutive processes of the above type \end{center} -\vspace*{0.3cm} -\end{minipage} -} -\begin{minipage}{0.3cm} -\hfill -\end{minipage} -\begin{minipage}{6.5cm} -VASP results -\begin{itemize} - \item Energetically most favorable path - \begin{itemize} - \item Path 2 - \item Activation energy: $\approx$ 0.9 eV - \item Experimental values: 0.73 ... 0.87 eV - \end{itemize} - $\Rightarrow$ {\color{blue}Diffusion} path identified! - \item Reorientation (path 3) - \begin{itemize} - \item More likely composed of two consecutive steps of type 2 - \item Experimental values: 0.77 ... 0.88 eV - \end{itemize} - $\Rightarrow$ {\color{blue}Reorientation} transition identified! -\end{itemize} -\end{minipage} \end{slide} \begin{slide} - {\large\bf\boldmath - Migration of the C \hkl<1 0 0> dumbbell interstitial - } +\headphd +{\large\bf\boldmath + C interstitial migration --- analytical potential +} \scriptsize - \vspace{0.1cm} - -\begin{minipage}{6.5cm} - -\framebox{ -\begin{minipage}[t]{5.9cm} -\begin{flushleft} -\includegraphics[width=5.9cm]{bc_00-1.ps}\\[2.35cm] -\end{flushleft} -\begin{center} -\begin{pspicture}(0,0)(0,0) -\psframe[linecolor=red,fillstyle=none](-2.8,1.35)(3.3,2.7) -\end{pspicture} -\begin{picture}(0,0)(60,-50) -\includegraphics[width=1cm]{albe_mig/bc_00-1_red_00.eps} -\end{picture} -\begin{picture}(0,0)(5,-50) -\includegraphics[width=1cm]{albe_mig/bc_00-1_red_01.eps} -\end{picture} -\begin{picture}(0,0)(-55,-50) -\includegraphics[width=1cm]{albe_mig/bc_00-1_red_02.eps} -\end{picture} -\begin{picture}(0,0)(12.5,-40) -\includegraphics[width=1cm]{110_arrow.eps} -\end{picture} -\begin{picture}(0,0)(90,-45) -\includegraphics[height=0.9cm]{001_arrow.eps} -\end{picture}\\ -\begin{pspicture}(0,0)(0,0) -\psframe[linecolor=blue,fillstyle=none](-2.8,0)(3.3,1.6) -\end{pspicture} -\begin{picture}(0,0)(60,-15) -\includegraphics[width=0.9cm]{albe_mig/bc_00-1_01.eps} -\end{picture} -\begin{picture}(0,0)(35,-15) -\includegraphics[width=0.9cm]{albe_mig/bc_00-1_02.eps} -\end{picture} -\begin{picture}(0,0)(-5,-15) -\includegraphics[width=0.9cm]{albe_mig/bc_00-1_03.eps} -\end{picture} -\begin{picture}(0,0)(-55,-15) -\includegraphics[width=0.9cm]{albe_mig/bc_00-1_04.eps} -\end{picture} -\begin{picture}(0,0)(12.5,-5) -\includegraphics[width=1cm]{100_arrow.eps} -\end{picture} -\begin{picture}(0,0)(90,-15) -\includegraphics[height=0.9cm]{010_arrow.eps} -\end{picture} -\end{center} -\end{minipage} -}\\[0.1cm] +\vspace{0.3cm} -\begin{minipage}{5.9cm} -Erhart/Albe results +\begin{minipage}[t]{6.0cm} +{\bf\boldmath BC to \hkl[0 0 -1] transition}\\[0.2cm] +\includegraphics[width=6.0cm]{bc_00-1_albe_s.ps}\\ \begin{itemize} - \item Lowest activation energy: $\approx$ 2.2 eV - \item 2.4 times higher than VASP + \item Lowermost migration barrier + \item $\Delta E \approx \unit[2.2]{eV}$ + \item 2.4 times higher than ab initio result \item Different pathway \end{itemize} \end{minipage} - -\end{minipage} -\begin{minipage}{6.5cm} - -\framebox{ -\begin{minipage}{5.9cm} -%\begin{flushright} -%\includegraphics[width=5.9cm]{00-1_0-10.ps}\\[0.75cm] -%\end{flushright} -%\begin{center} -%\begin{pspicture}(0,0)(0,0) -%\psframe[linecolor=red,fillstyle=none](-2.8,-0.25)(3.3,1.1) -%\end{pspicture} -%\begin{picture}(0,0)(60,-5) -%\includegraphics[width=0.9cm]{albe_mig/00-1_0-10_red_00.eps} -%\end{picture} -%\begin{picture}(0,0)(0,-5) -%\includegraphics[width=0.9cm]{albe_mig/00-1_0-10_red_min.eps} -%\end{picture} -%\begin{picture}(0,0)(-55,-5) -%\includegraphics[width=0.9cm]{albe_mig/00-1_0-10_red_03.eps} -%\end{picture} -%\begin{picture}(0,0)(12.5,5) -%\includegraphics[width=1cm]{100_arrow.eps} -%\end{picture} -%\begin{picture}(0,0)(90,0) -%\includegraphics[height=0.9cm]{001_arrow.eps} -%\end{picture} -%\end{center} -%\vspace{0.2cm} -%\end{minipage} -%}\\[0.2cm] -% -%\framebox{ -%\begin{minipage}{5.9cm} -\includegraphics[width=5.9cm]{00-1_110_0-10_mig_albe.ps} +\begin{minipage}[t]{0.2cm} +\hfill \end{minipage} -}\\[0.1cm] - -\begin{minipage}{5.9cm} -Transition involving \ci{} \hkl<1 1 0> +\begin{minipage}[t]{6.0cm} +{\bf\boldmath Transition involving a \hkl<1 1 0> configuration} +\vspace{0.1cm} \begin{itemize} \item Bond-centered configuration unstable\\ $\rightarrow$ \ci{} \hkl<1 1 0> dumbbell - \item Transition minima of path 2 \& 3\\ - $\rightarrow$ \ci{} \hkl<1 1 0> dumbbell - \item Activation energy: $\approx$ 2.2 eV \& 0.9 eV - \item 2.4 - 3.4 times higher than VASP - \item Rotation of dumbbell orientation + \item Minima of the \hkl[0 0 -1] to \hkl[0 -1 0] transition\\ + $\rightarrow$ \ci{} \hkl<1 1 0> DB \end{itemize} \vspace{0.1cm} +\includegraphics[width=6.0cm]{00-1_110_0-10_mig_albe.ps} +\begin{itemize} + \item $\Delta E \approx \unit[2.2]{eV} \text{ \& } \unit[0.9]{eV}$ + \item 2.4 -- 3.4 times higher than ab initio result + \item After all: Change of the DB orientation +\end{itemize} +\end{minipage} + +\vspace{0.5cm} \begin{center} -{\color{blue}Overestimated diffusion barrier} +{\color{red}\bf Drastically overestimated diffusion barrier} \end{center} -\end{minipage} -\end{minipage} +\begin{pspicture}(0,0)(0,0) +\psline[linewidth=0.05cm,linecolor=gray](6.1,1.0)(6.1,9.3) +\end{pspicture} \end{slide} \begin{slide} - {\large\bf\boldmath - Combinations with a C-Si \hkl<1 0 0>-type interstitial - } - -\small - -\vspace*{0.1cm} +\headphd +{\large\bf\boldmath + Defect combinations +} -Binding energy: -$ -E_{\text{b}}= -E_{\text{f}}^{\text{defect combination}}- -E_{\text{f}}^{\text{C \hkl<0 0 -1> dumbbell}}- -E_{\text{f}}^{\text{2nd defect}} -$ +\footnotesize -\vspace*{0.1cm} +\vspace{0.3cm} +\begin{minipage}{9cm} +{\bf + Summary of combinations}\\[0.1cm] {\scriptsize \begin{tabular}{l c c c c c c} \hline $E_{\text{b}}$ [eV] & 1 & 2 & 3 & 4 & 5 & R\\ \hline - \hkl<0 0 -1> & {\color{red}-0.08} & -1.15 & {\color{red}-0.08} & 0.04 & -1.66 & -0.19\\ - \hkl<0 0 1> & 0.34 & 0.004 & -2.05 & 0.26 & -1.53 & -0.19\\ - \hkl<0 -1 0> & {\color{orange}-2.39} & -0.17 & {\color{green}-0.10} & {\color{blue}-0.27} & {\color{magenta}-1.88} & {\color{gray}-0.05}\\ - \hkl<0 1 0> & {\color{cyan}-2.25} & -1.90 & {\color{cyan}-2.25} & {\color{purple}-0.12} & {\color{violet}-1.38} & {\color{yellow}-0.06}\\ - \hkl<-1 0 0> & {\color{orange}-2.39} & -0.36 & {\color{cyan}-2.25} & {\color{purple}-0.12} & {\color{magenta}-1.88} & {\color{gray}-0.05}\\ - \hkl<1 0 0> & {\color{cyan}-2.25} & -2.16 & {\color{green}-0.10} & {\color{blue}-0.27} & {\color{violet}-1.38} & {\color{yellow}-0.06}\\ + \hkl[0 0 -1] & {\color{red}-0.08} & -1.15 & {\color{red}-0.08} & 0.04 & -1.66 & -0.19\\ + \hkl[0 0 1] & 0.34 & 0.004 & -2.05 & 0.26 & -1.53 & -0.19\\ + \hkl[0 -1 0] & {\color{orange}-2.39} & -0.17 & {\color{green}-0.10} & {\color{blue}-0.27} & {\color{magenta}-1.88} & {\color{gray}-0.05}\\ + \hkl[0 1 0] & {\color{cyan}-2.25} & -1.90 & {\color{cyan}-2.25} & {\color{purple}-0.12} & {\color{violet}-1.38} & {\color{yellow}-0.06}\\ + \hkl[-1 0 0] & {\color{orange}-2.39} & -0.36 & {\color{cyan}-2.25} & {\color{purple}-0.12} & {\color{magenta}-1.88} & {\color{gray}-0.05}\\ + \hkl[1 0 0] & {\color{cyan}-2.25} & -2.16 & {\color{green}-0.10} & {\color{blue}-0.27} & {\color{violet}-1.38} & {\color{yellow}-0.06}\\ \hline - C substitutional (C$_{\text{S}}$) & 0.26 & -0.51 & -0.93 & -0.15 & 0.49 & -0.05\\ - Vacancy & -5.39 ($\rightarrow$ C$_{\text{S}}$) & -0.59 & -3.14 & -0.54 & -0.50 & -0.31\\ + C$_{\text{sub}}$ & 0.26 & -0.51 & -0.93 & -0.15 & 0.49 & -0.05\\ + Vacancy & -5.39 ($\rightarrow$ C$_{\text{sub}}$) & -0.59 & -3.14 & -0.54 & -0.50 & -0.31\\ \hline \end{tabular} } +\vspace{0.2cm} +\begin{center} +{\color{blue} + $E_{\text{b}}$ explainable by stress compensation / increase +} +\end{center} +\end{minipage} +\begin{minipage}{3cm} +\includegraphics[width=3.5cm]{comb_pos.eps} +\end{minipage} -\vspace*{0.3cm} - -\footnotesize +\vspace{0.2cm} -\begin{minipage}[t]{3.8cm} -\underline{\hkl<1 0 0> at position 1}\\[0.1cm] -\includegraphics[width=3.5cm]{00-1dc/2-25.eps} +{\bf\boldmath Combinations of \hkl<1 0 0>-type interstitials}\\[0.2cm] +\begin{minipage}[t]{3.2cm} +\underline{\hkl[1 0 0] at position 1}\\[0.1cm] +\includegraphics[width=2.8cm]{00-1dc/2-25.eps} \end{minipage} -\begin{minipage}[t]{3.5cm} -\underline{\hkl<0 -1 0> at position 1}\\[0.1cm] -\includegraphics[width=3.2cm]{00-1dc/2-39.eps} +\begin{minipage}[t]{3.0cm} +\underline{\hkl[0 -1 0] at position 1}\\[0.1cm] +\includegraphics[width=2.8cm]{00-1dc/2-39.eps} \end{minipage} -\begin{minipage}[t]{5.5cm} +\begin{minipage}[t]{6.1cm} +\vspace{0.7cm} \begin{itemize} - \item $E_{\text{b}}=0$ $\Leftrightarrow$ non-interacting defects\\ - $E_{\text{b}} \rightarrow 0$ for increasing distance (R) - \item Stress compensation / increase - \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) + \item \ci{} agglomeration energetically favorable + \item Most favorable: C clustering\\ + {\color{red}However \ldots}\\ + \ldots high migration barrier ($>4\,\text{eV}$)\\ + \ldots entropy: + $4\times{\color{cyan}[-2.25]}$ versus + $2\times{\color{orange}[-2.39]}$ \end{itemize} +\begin{center} +{\color{blue}\ci{} agglomeration / no C clustering} +\end{center} \end{minipage} -\begin{picture}(0,0)(-295,-130) -\includegraphics[width=3.5cm]{comb_pos.eps} -\end{picture} - \end{slide} \begin{slide} - {\large\bf\boldmath - Combinations of C-Si \hkl<1 0 0>-type interstitials - } - -\small - -\vspace*{0.1cm} +\headphd +{\large\bf\boldmath + Defect combinations +} -Energetically most favorable combinations along \hkl<1 1 0> +\footnotesize -\vspace*{0.1cm} +\vspace{0.3cm} +\begin{minipage}{9cm} +{\bf + Summary of combinations}\\[0.1cm] {\scriptsize \begin{tabular}{l c c c c c c} \hline - & 1 & 2 & 3 & 4 & 5 & 6\\ -\hline -$E_{\text{b}}$ [eV] & -2.39 & -1.88 & -0.59 & -0.31 & -0.24 & -0.21 \\ -C-C distance [\AA] & 1.4 & 4.6 & 6.5 & 8.6 & 10.5 & 10.8 \\ -Type & \hkl<-1 0 0> & \hkl<1 0 0> & \hkl<1 0 0> & \hkl<1 0 0> & \hkl<1 0 0> & \hkl<1 0 0>, \hkl<0 -1 0>\\ + $E_{\text{b}}$ [eV] & 1 & 2 & 3 & 4 & 5 & R\\ + \hline + \hkl[0 0 -1] & {\color{red}-0.08} & -1.15 & {\color{red}-0.08} & 0.04 & -1.66 & -0.19\\ + \hkl[0 0 1] & 0.34 & 0.004 & -2.05 & 0.26 & -1.53 & -0.19\\ + \hkl[0 -1 0] & {\color{orange}-2.39} & -0.17 & {\color{green}-0.10} & {\color{blue}-0.27} & {\color{magenta}-1.88} & {\color{gray}-0.05}\\ + \hkl[0 1 0] & {\color{cyan}-2.25} & -1.90 & {\color{cyan}-2.25} & {\color{purple}-0.12} & {\color{violet}-1.38} & {\color{yellow}-0.06}\\ + \hkl[-1 0 0] & {\color{orange}-2.39} & -0.36 & {\color{cyan}-2.25} & {\color{purple}-0.12} & {\color{magenta}-1.88} & {\color{gray}-0.05}\\ + \hkl[1 0 0] & {\color{cyan}-2.25} & -2.16 & {\color{green}-0.10} & {\color{blue}-0.27} & {\color{violet}-1.38} & {\color{yellow}-0.06}\\ + \hline + C$_{\text{sub}}$ & 0.26 & -0.51 & -0.93 & -0.15 & 0.49 & -0.05\\ + Vacancy & -5.39 ($\rightarrow$ C$_{\text{sub}}$) & -0.59 & -3.14 & -0.54 & -0.50 & -0.31\\ \hline \end{tabular} } +\vspace{0.2cm} +\begin{center} +{\color{blue} + $E_{\text{b}}$ explainable by stress compensation / increase +} +\end{center} +\end{minipage} +\begin{minipage}{3cm} +\includegraphics[width=3.5cm]{comb_pos.eps} +\end{minipage} -\vspace*{0.3cm} +\vspace{0.2cm} -\begin{minipage}{7.0cm} -\includegraphics[width=7cm]{db_along_110_cc.ps} +{\bf\boldmath Combinations of \hkl<1 0 0>-type interstitials}\\[0.2cm] +\begin{minipage}[t]{3.2cm} +\underline{\hkl[1 0 0] at position 1}\\[0.1cm] +\includegraphics[width=2.8cm]{00-1dc/2-25.eps} \end{minipage} -\begin{minipage}{6.0cm} +\begin{minipage}[t]{3.0cm} +\underline{\hkl[0 -1 0] at position 1}\\[0.1cm] +\includegraphics[width=2.8cm]{00-1dc/2-39.eps} +\end{minipage} +\begin{minipage}[t]{6.1cm} +\vspace{0.7cm} \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 + \item \ci{} agglomeration energetically favorable + \item Most favorable: C clustering\\ + {\color{red}However \ldots}\\ + \ldots high migration barrier ($>4\,\text{eV}$)\\ + \ldots entropy: + $4\times{\color{cyan}[-2.25]}$ versus + $2\times{\color{orange}[-2.39]}$ \end{itemize} \begin{center} -{\color{blue} - Consisten with initial precipitation model -} +{\color{blue}\ci{} agglomeration / no C clustering} \end{center} \end{minipage} +% insert graph ... +\begin{pspicture}(0,0)(0,0) +\rput(6.5,5.0){\psframebox[fillstyle=solid,opacity=0.5,fillcolor=black]{ +\begin{minipage}{14cm} +\hfill +\vspace{12cm} +\end{minipage} +}} +\rput(6.5,5.3){\rnode{init}{\psframebox[fillstyle=solid,fillcolor=white,linewidth=0.1cm]{ +\begin{minipage}{8cm} +\begin{center} \vspace{0.2cm} +\scriptsize +Interaction along \hkl[1 1 0] +\includegraphics[width=7cm]{db_along_110_cc.ps} +\end{center} +\end{minipage} +}}} +\end{pspicture} \end{slide} \begin{slide} - {\large\bf\boldmath - Combinations of substitutional C and \hkl<1 1 0> Si self-interstitials - } - - \scriptsize +\headphd +{\large\bf + Defect combinations of C-Si dimers and vacancies +} +\footnotesize -%\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} +\vspace{0.2cm} -\begin{minipage}{6.0cm} -\includegraphics[width=5.8cm]{c_sub_si110.ps} +\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}{7cm} -\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 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\\ - $\rightarrow$ low capture radius -\end{itemize} -\begin{center} - {\color{blue} - IBS process far from equilibrium\\ - \cs{} \& \si{} instead of thermodynamic ground state - } -\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}{6.5cm} -\includegraphics[width=6.0cm]{162-097.ps} -\begin{itemize} - \item Low migration barrier -\end{itemize} +\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) + +\rput(6.3,7.0){\rnode{init}{\psframebox[fillstyle=solid,fillcolor=white,linewidth=0.05cm,linecolor=gray]{ \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} +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} -Contribution of entropy to structural formation +High probability of stable C$_{\text{sub}}$ configuration } +\end{center} \end{minipage} +}}} +\end{pspicture} \end{slide} \begin{slide} - {\large\bf\boldmath - Migration in C-Si \hkl<1 0 0> and vacancy combinations - } +\headphd +{\large\bf + Combinations of substitutional C and Si self-interstitials +} - \footnotesize +\scriptsize -\vspace{0.1cm} +\vspace{0.3cm} -\begin{minipage}[t]{3cm} -\underline{Pos 2, $E_{\text{b}}=-0.59\text{ eV}$}\\ -\includegraphics[width=2.8cm]{00-1dc/0-59.eps} -\end{minipage} -\begin{minipage}[t]{7cm} -\vspace{0.2cm} +\begin{minipage}{6.2cm} \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} - +{\bf\boldmath C$_{\text{sub}}$ - \si{} \hkl<1 1 0> interaction} +\begin{itemize} + \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} \end{center} \end{minipage} -\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}{0.2cm} +\hfill \end{minipage} - - -\framebox{ -\begin{minipage}{5.9cm} -\includegraphics[width=5.9cm]{vasp_mig/comb_mig_3-2_vac_fullct.ps}\\[0.6cm] +\begin{minipage}{6.0cm} \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} +{\bf Transition from the ground state} +\begin{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} -\vspace{0.1cm} +\end{minipage}\\[0.3cm] + +\begin{minipage}{6.0cm} +\includegraphics[width=6.0cm]{c_sub_si110.ps} \end{minipage} -} -\begin{minipage}{0.3cm} +\begin{minipage}{0.4cm} \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} +\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} +\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} +\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} -{\color{blue}Results suggest increased participation of \cs} +\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) @@ -2079,7 +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} @@ -2090,227 +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) - -\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} -\end{minipage} -} -\end{picture} +Accelerated methods or higher time scales exclusively not sufficient! -\begin{picture}(0,0)(-305,-155) -\framebox{ -\begin{minipage}{2.5cm} +\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} +}} +\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} @@ -2337,40 +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} @@ -2397,40 +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 @@ -2497,68 +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} @@ -2610,4 +2570,3 @@ High C \& low T implants \end{document} -\fi