X-Git-Url: https://hackdaworld.org/gitweb/?p=lectures%2Flatex.git;a=blobdiff_plain;f=posic%2Ftalks%2Fdefense.tex;h=8757367110f89b7d2c7fc854932443825ded9bfc;hp=e0f334deb00ebf20bef389b22e56734e3739ebb6;hb=42570daa4910e1b47c0469cd2fc8a01a5c7a4003;hpb=bb741b8e0c861ccd0f8751734fa967691665de9a diff --git a/posic/talks/defense.tex b/posic/talks/defense.tex index e0f334d..8757367 100644 --- a/posic/talks/defense.tex +++ b/posic/talks/defense.tex @@ -248,101 +248,6 @@ E\\ % fabrication -\ifnum1=0 -\begin{slide} - -\headphd - {\large\bf - Fabrication of silicon carbide - } - - \small - - \vspace{2pt} - -\begin{center} - {\color{gray} - \emph{Silicon carbide --- Born from the stars, perfected on earth.} - } -\end{center} - -\vspace{2pt} - -SiC thin films by MBE \& CVD -\begin{itemize} - \item Much progress achieved in homo/heteroepitaxial SiC thin film growth - \item \underline{Commercially available} semiconductor power devices based on - \underline{\foreignlanguage{greek}{a}-SiC} - \item Production of favored \underline{3C-SiC} material - \underline{less advanced} - \item Quality and size not yet sufficient -\end{itemize} -\begin{picture}(0,0)(-310,-20) - \includegraphics[width=2.0cm]{cree.eps} -\end{picture} - -\vspace{-0.5cm} - -%\begin{center} -%\color{red} -%\framebox{ -%{\footnotesize\color{black} -% Mismatch in \underline{thermal expansion coeefficient} -% and \underline{lattice parameter} w.r.t. substrate -%} -%} -%\end{center} - -\vspace{0.1cm} - -{\bf Alternative approach}\\ -Ion beam synthesis (IBS) of burried 3C-SiC layers in Si\hkl(1 0 0) - -\vspace{0.1cm} - -\scriptsize - -\framebox{ -\begin{minipage}{3.15cm} - \begin{center} -\includegraphics[width=3cm]{imp.eps}\\ - {\tiny - Carbon implantation - } - \end{center} -\end{minipage} -\begin{minipage}{3.15cm} - \begin{center} -\includegraphics[width=3cm]{annealing.eps}\\ - {\tiny - Postannealing at $>$ \degc{1200} - } - \end{center} -\end{minipage} -} -\begin{minipage}{5.5cm} - \includegraphics[width=5.8cm]{ibs_3c-sic.eps}\\[-0.2cm] - \begin{center} - {\tiny - XTEM: single crystalline 3C-SiC in Si\hkl(1 0 0) - } - \end{center} -\end{minipage} - -%\begin{minipage}{5.5cm} -%\begin{center} -%{\footnotesize -%No surface bending effects\\ -%High areal homogenity\\[0.1cm] -%$\Downarrow$\\[0.1cm] -%Synthesis of large area SiC films possible -%} -%\end{center} -%\end{minipage} - -\end{slide} -\fi - \begin{slide} \headphd @@ -389,15 +294,15 @@ Ion beam synthesis (IBS) of burried 3C-SiC layers in Si\hkl(1 0 0) not yet fully understood } \end{center} - \vspace*{0.1cm} - \renewcommand\labelitemi{$\Rightarrow$} - 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 - \end{itemize} +% \vspace*{0.1cm} +% \renewcommand\labelitemi{$\Rightarrow$} +% 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 +% \end{itemize} \end{minipage} }} \rput(-6.8,5.5){\pnode{h0}} @@ -648,11 +553,11 @@ r = \unit[2--4]{nm} \end{itemize} $\Rightarrow$ mobile {\color{red}\ci} opposed to stable {\color{blue}\cs{}} configurations -\item Strained silicon \& Si$_{1-y}$C$_y$ heterostructures +\item Strained Si$_{1-y}$C$_y$/Si heterostructures {\tiny\color{gray}/Strane~et~al./Guedj~et~al./} \begin{itemize} - \item Initial {\color{blue}coherent} SiC precipitates (tensile strain) - \item Incoherent SiC (strain relaxation) + \item Initial {\color{blue}coherent} SiC structures (tensile strain) + \item Incoherent SiC nanocrystals (strain relaxation) \end{itemize} \end{itemize} \vspace{0.1cm} @@ -846,13 +751,13 @@ $ \end{minipage} \end{minipage} -\vspace{0.2cm} +\vspace{0.3cm} -\begin{minipage}[b]{6cm} +\begin{minipage}[t]{6cm} {\bf Defect formation energy}\\ \framebox{ -$E_{\text{f}}=E-\sum_i N_i\mu_i$}\\[0.1cm] -Particle reservoir: Si \& SiC\\[0.2cm] +$E_{\text{f}}=E-\sum_i N_i\mu_i$}\\[0.5cm] +%Particle reservoir: Si \& SiC\\[0.2cm] {\bf Binding energy}\\ \framebox{ $ @@ -866,7 +771,8 @@ $ $E_{\text{b}}<0$: energetically favorable configuration\\ $E_{\text{b}}\rightarrow 0$: non-interacting, isolated defects\\ \end{minipage} -\begin{minipage}[b]{6cm} +\begin{minipage}[t]{6cm} +\vspace{1.4cm} {\bf Migration barrier} \footnotesize \begin{itemize} @@ -1056,7 +962,7 @@ Note: Change in orientation \begin{itemize} \item Bond-centered configuration unstable\\ $\rightarrow$ \ci{} \hkl<1 1 0> dumbbell - \item Minima of the \hkl[0 0 -1] to \hkl[0 -1 0] transition\\ + \item Minimum of the \hkl[0 0 -1] to \hkl[0 -1 0] transition\\ $\rightarrow$ \ci{} \hkl<1 1 0> DB \end{itemize} \vspace{0.1cm} @@ -1561,7 +1467,7 @@ $\rightarrow$ Consider $V_2$ and $V_3$ \begin{minipage}{6.1cm} \scriptsize \underline{Low C concentration --- {\color{red}$V_1$}}\\[0.1cm] -\hkl<1 0 0> C-Si dumbbell dominated structure +\ci{} \hkl<1 0 0> dumbbell dominated structure \begin{itemize} \item Si-C bumbs around \unit[0.19]{nm} \item C-C peak at \unit[0.31]{nm} (expected in 3C-SiC):\\ @@ -1573,7 +1479,7 @@ $\rightarrow$ Consider $V_2$ and $V_3$ \begin{minipage}{6cm} \centering Formation of \ci{} dumbbells\\ -C atoms in proper 3C-SiC distance first +C atoms separated as expected in 3C-SiC \end{minipage} }} \end{pspicture}\\[0.1cm] @@ -1621,7 +1527,7 @@ Amorphous SiC-like phase \begin{minipage}{6.1cm} \scriptsize \underline{Low C concentration --- {\color{red}$V_1$}}\\[0.1cm] -\hkl<1 0 0> C-Si dumbbell dominated structure +\ci{} \hkl<1 0 0> dumbbell dominated structure \begin{itemize} \item Si-C bumbs around \unit[0.19]{nm} \item C-C peak at \unit[0.31]{nm} (expected in 3C-SiC):\\ @@ -1633,7 +1539,7 @@ Amorphous SiC-like phase \begin{minipage}{6cm} \centering Formation of \ci{} dumbbells\\ -C atoms in proper 3C-SiC distance first +C atoms separated as expected in 3C-SiC \end{minipage} }} \end{pspicture}\\[0.1cm] @@ -1692,7 +1598,7 @@ No rearrangement/transition into 3C-SiC \vspace{0.2cm} {\bf Time scale problem of MD}\\[0.2cm] -Precise integration \& thermodynamic sampling\\ +Minimize integration error \& precise thermodynamic sampling\\ $\Rightarrow$ $\Delta t \ll \left( \max{\omega} \right)^{-1}$, $\omega$: vibrational mode\\ $\Rightarrow$ {\color{red}\underline{Slow}} phase space propagation\\[0.2cm] @@ -1775,7 +1681,8 @@ equilibrium properties \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$_{\text{sub}}$ + \item Structural change: \ci{} \hkl<1 0 0> DB $\rightarrow$ + {\color{blue}\cs{}} \end{itemize} \underline{Si-Si bonds:} {\color{blue}Si-C$_{\text{sub}}$-Si} along \hkl<1 1 0> @@ -1783,17 +1690,11 @@ equilibrium properties \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} + \item Peak at 0.3 nm slightly shifted\\[0.05cm] + $\searrow$ \ci{} combinations (dashed arrows)\\ + $\nearrow$ \ci{} \hkl<1 0 0> \& {\color{blue}\cs{} combinations} (|)\\ + $\nearrow$ \ci{} pure \cs{} combinations ($\Downarrow$)\\[0.05cm] + Range [|-$\downarrow$]: {\color{blue}\cs{} \& \cs{} with nearby \si} \end{itemize} \end{minipage} @@ -1834,16 +1735,11 @@ equilibrium properties \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} + \item Peak at 0.3 nm slightly shifted\\[0.05cm] + $\searrow$ \ci{} combinations (dashed arrows)\\ + $\nearrow$ \ci{} \hkl<1 0 0> \& {\color{blue}\cs{} combinations} (|)\\ + $\nearrow$ \ci{} pure \cs{} combinations ($\Downarrow$)\\[0.05cm] + Range [|-$\downarrow$]: {\color{blue}\cs{} \& \cs{} with nearby \si} \end{itemize} \end{minipage} @@ -1864,9 +1760,16 @@ equilibrium properties {\Huge$\lightning$} {\color{red}\ci{}} --- vs --- {\color{blue}\cs{}} {\Huge$\lightning$}\\ \end{center} \begin{itemize} -\item Stretched coherent SiC structures\\ -$\Rightarrow$ Precipitation process involves {\color{blue}\cs} -\item Role of \si{} +\item Stretched coherent SiC structures directly observed +\begin{center} +\psframebox[linecolor=blue,linewidth=0.05cm]{ +\begin{minipage}{7cm} +\centering +\cs{} extensively involved in the precipitation mechanism\\ +\end{minipage} +} +\end{center} +\item Emission of \si{} serves several needs: \begin{itemize} \item Vehicle to rearrange \cs --- [\cs{} \& \si{} $\leftrightarrow$ \ci] \item Building block for surrounding Si host \& further SiC @@ -1885,7 +1788,6 @@ $\Rightarrow$ Precipitation process involves {\color{blue}\cs} \psframebox[linecolor=blue,linewidth=0.05cm]{ \begin{minipage}{7cm} \centering -Precipitation mechanism involving \cs\\ High T $\leftrightarrow$ IBS conditions far from equilibrium\\ \end{minipage} } @@ -1968,9 +1870,6 @@ High C \& low T implants % skip high c conc \fi -% for preparation -%\fi - \begin{slide} \headphd @@ -1993,7 +1892,7 @@ High C \& low T implants \item Identified \ci{} migration path \item EA drastically overestimates the diffusion barrier \end{itemize} - \item Combinations of defects + \item Combinations of defects (DFT) \begin{itemize} \item Agglomeration of point defects energetically favorable \item C$_{\text{sub}}$ favored conditions (conceivable in IBS) @@ -2044,6 +1943,7 @@ High C \& low T implants \begin{itemize} \item Prof. B. Stritzker \item Ralf Utermann + \item EP \RM{4} \end{itemize} \underline{Helsinki} @@ -2063,13 +1963,14 @@ High C \& low T implants \item Dr. E. Rauls \end{itemize} -\vspace{ 0.2cm} +\vspace{0.2cm} \begin{center} \framebox{ \normalsize\bf Thank you for your attention! } \end{center} +Referees: PD V. Eyert \& Prof. Haider \end{slide}