X-Git-Url: https://hackdaworld.org/gitweb/?a=blobdiff_plain;f=posic%2Ftalks%2Fseminar_2010.tex;h=67de04d36939ec3fa44fb48e55d1ba77425e5167;hb=95b2d1acc7fb1969b13df81cf5c3e0eeea913dff;hp=fd742bb16a7af6f81c6f1b287771f32ea9bb6208;hpb=3d5577359a78be2b7cf1f2fa6ab2db587f749f8f;p=lectures%2Flatex.git diff --git a/posic/talks/seminar_2010.tex b/posic/talks/seminar_2010.tex index fd742bb..67de04d 100644 --- a/posic/talks/seminar_2010.tex +++ b/posic/talks/seminar_2010.tex @@ -26,6 +26,8 @@ \usepackage{graphicx} \graphicspath{{../img/}} +\usepackage{miller} + \usepackage[setpagesize=false]{hyperref} \usepackage{semcolor} @@ -172,14 +174,14 @@ } \begin{itemize} - \item Fabrication of silicon carbide - \item Precipitation model + \item Polyteps and fabrication of silicon carbide + \item Supposed precipitation mechanism of SiC in Si \item Utilized simulation techniques \begin{itemize} \item Molecular dynamics (MD) simulations \item Density functional theory (DFT) calculations \end{itemize} - \item Point defects in silicon + \item C and Si self-interstitial point defects in silicon \item Precipitation simulations \item Summary / Conclusion / Outlook \end{itemize} @@ -191,51 +193,247 @@ \begin{slide} {\large\bf - Motivation + Polytypes of SiC + } + + \vspace{4cm} + + \small + +\begin{tabular}{l c c c c c c} +\hline + & 3C-SiC & 4H-SiC & 6H-SiC & Si & GaN & Diamond\\ +\hline +Hardness [Mohs] & \multicolumn{3}{c}{------ 9.6 ------}& 6.5 & - & 10 \\ +Band gap [eV] & 2.36 & 3.23 & 3.03 & 1.12 & 3.39 & 5.5 \\ +Break down field [$10^6$ V/cm] & 4 & 3 & 3.2 & 0.6 & 5 & 10 \\ +Saturation drift velocity [$10^7$ cm/s] & 2.5 & 2.0 & 2.0 & 1 & 2.7 & 2.7 \\ +Electron mobility [cm$^2$/Vs] & 800 & 900 & 400 & 1100 & 900 & 2200 \\ +Hole mobility [cm$^2$/Vs] & 320 & 120 & 90 & 420 & 150 & 1600 \\ +Thermal conductivity [W/cmK] & 5.0 & 4.9 & 4.9 & 1.5 & 1.3 & 22 \\ +\hline +\end{tabular} + +{\tiny + Values for $T=300$ K +} + +\begin{picture}(0,0)(-160,-155) + \includegraphics[width=7cm]{polytypes.eps} +\end{picture} +\begin{picture}(0,0)(-10,-185) + \includegraphics[width=3.8cm]{cubic_hex.eps}\\ +\end{picture} +\begin{picture}(0,0)(-10,-175) + {\tiny cubic (twist)} +\end{picture} +\begin{picture}(0,0)(-60,-175) + {\tiny hexagonal (no twist)} +\end{picture} +\begin{pspicture}(0,0)(0,0) +\psellipse[linecolor=green](5.7,3.03)(0.4,0.5) +\end{pspicture} +\begin{pspicture}(0,0)(0,0) +\psellipse[linecolor=green](5.6,1.68)(0.4,0.2) +\end{pspicture} +\begin{pspicture}(0,0)(0,0) +\psellipse[linecolor=red](10.7,1.13)(0.4,0.2) +\end{pspicture} + +\end{slide} + +\begin{slide} + + {\large\bf + Fabrication of silicon carbide } + + \small \vspace{4pt} SiC - \emph{Born from the stars, perfected on earth.} - + \vspace{4pt} - Herstellung d"unner SiC-Filme: + Conventional thin film SiC growth: \begin{itemize} - \item modifizierter Lely-Prozess + \item \underline{Sublimation growth using the modified Lely method} \begin{itemize} - \item Impfkristall mit $T=2200 \, ^{\circ} \text{C}$ - \item umgeben von polykristallinen SiC mit - $T=2400 \, ^{\circ} \text{C}$ + \item SiC single-crystalline seed at $T=1800 \, ^{\circ} \text{C}$ + \item Surrounded by polycrystalline SiC in a graphite crucible\\ + at $T=2100-2400 \, ^{\circ} \text{C}$ + \item Deposition of supersaturated vapor on cooler seed crystal \end{itemize} - \item CVD Homoepitaxie + \item \underline{Homoepitaxial growth using CVD} \begin{itemize} - \item 'step controlled epitaxy' auf 6H-SiC-Substrat - \item C$_3$H$_8$/SiH$_4$/H$_2$ bei $1500 \, ^{\circ} \text{C}$ - \item Winkel $\rightarrow$ 3C/6H/4H-SiC - \item hohe Qualit"at aber limitiert durch\\ - Substratgr"o"se + \item Step-controlled epitaxy on off-oriented 6H-SiC substrates + \item C$_3$H$_8$/SiH$_4$/H$_2$ at $1100-1500 \, ^{\circ} \text{C}$ + \item Angle, temperature $\rightarrow$ 3C/6H/4H-SiC + \item High quality but limited in size of substrates \end{itemize} - \item CVD/MBE Heteroepitaxie von 3C-SiC auf Si + \item \underline{Heteroepitaxial growth of 3C-SiC on Si using CVD/MBE} \begin{itemize} - \item 2 Schritte: Karbonisierung und Wachstum + \item Two steps: carbonization and growth \item $T=650-1050 \, ^{\circ} \text{C}$ - \item Qualit"at/Gr"o"se noch nicht ausreichend + \item Quality and size not yet sufficient \end{itemize} \end{itemize} - \begin{picture}(0,0)(-245,-50) - \includegraphics[width=5cm]{6h-sic_3c-sic.eps} + \begin{picture}(0,0)(-280,-65) + \includegraphics[width=3.8cm]{6h-sic_3c-sic.eps} + \end{picture} + \begin{picture}(0,0)(-280,-55) + \begin{minipage}{5cm} + {\tiny + NASA: 6H-SiC and 3C-SiC LED\\[-7pt] + on 6H-SiC substrate + } + \end{minipage} + \end{picture} + \begin{picture}(0,0)(-265,-150) + \includegraphics[width=2.4cm]{m_lely.eps} \end{picture} - \begin{picture}(0,0)(-240,-35) + \begin{picture}(0,0)(-333,-175) \begin{minipage}{5cm} - {\scriptsize - NASA: 6H-SiC LED und 3C-SiC LED\\[-6pt] - nebeneinander auf 6H-SiC-Substrat + {\tiny + 1. Lid\\[-7pt] + 2. Heating\\[-7pt] + 3. Source\\[-7pt] + 4. Crucible\\[-7pt] + 5. Insulation\\[-7pt] + 6. Seed crystal } \end{minipage} \end{picture} \end{slide} +\begin{slide} + + {\large\bf + Fabrication of silicon carbide + } + + \small + + Alternative approach: + Ion beam synthesis (IBS) of burried 3C-SiC layers in Si\hkl(1 0 0) + \begin{itemize} + \item \underline{Implantation step 1}\\ + 180 keV C$^+$, $D=7.9\times 10^{17}$ cm$^{-2}$, $T_{\text{i}}=500\,^{\circ}\mathrm{C}$\\ + $\Rightarrow$ box-like distribution of equally sized + and epitactically oriented SiC precipitates + + \item \underline{Implantation step 2}\\ + 180 keV C$^+$, $D=0.6\times 10^{17}$ cm$^{-2}$, $T_{\text{i}}=250\,^{\circ}\mathrm{C}$\\ + $\Rightarrow$ destruction of SiC nanocrystals + in growing amorphous interface layers + \item \underline{Annealing}\\ + $T=1250\,^{\circ}\mathrm{C}$, $t=10\,\text{h}$\\ + $\Rightarrow$ homogeneous, stoichiometric SiC layer + with sharp interfaces + \end{itemize} + + \begin{minipage}{6.3cm} + \includegraphics[width=6cm]{ibs_3c-sic.eps}\\[-0.2cm] + {\tiny + XTEM micrograph of single crystalline 3C-SiC in Si\hkl(1 0 0) + } + \end{minipage} + \begin{minipage}{6.3cm} + \begin{center} + {\color{blue}\bf\normalsize + Precipitation mechanism not yet fully understood! + } + \renewcommand\labelitemi{$\Rightarrow$} + \small + \underline{Understanding 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{center} + \end{minipage} + +\end{slide} + +\begin{slide} + + {\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 + \end{minipage} + \hspace{0.6cm} + \begin{minipage}{3.8cm} + \begin{center} + \includegraphics[width=3.3cm]{tem_c-si-db.eps} + \end{center} + \end{minipage} + \hspace{0.6cm} + \begin{minipage}{3.8cm} + \begin{center} + \includegraphics[width=3.3cm]{tem_3c-sic.eps} + \end{center} + \end{minipage} + + \begin{minipage}{4cm} + \begin{center} + C-Si dimers (dumbbells)\\[-0.1cm] + on Si interstitial sites + \end{center} + \end{minipage} + \hspace{0.2cm} + \begin{minipage}{4.2cm} + \begin{center} + Agglomeration of C-Si dumbbells\\[-0.1cm] + $\Rightarrow$ dark contrasts + \end{center} + \end{minipage} + \hspace{0.2cm} + \begin{minipage}{4cm} + \begin{center} + Precipitation of 3C-SiC in Si\\[-0.1cm] + $\Rightarrow$ Moir\'e fringes\\[-0.1cm] + \& release of Si self-interstitials + \end{center} + \end{minipage} + + \begin{minipage}{3.8cm} + \begin{center} + \includegraphics[width=3.3cm]{sic_prec_seq_01.eps} + \end{center} + \end{minipage} + \hspace{0.6cm} + \begin{minipage}{3.8cm} + \begin{center} + \includegraphics[width=3.3cm]{sic_prec_seq_02.eps} + \end{center} + \end{minipage} + \hspace{0.6cm} + \begin{minipage}{3.8cm} + \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)} +%\rput{-20}{\psellipse[linecolor=blue](6,6.5)(0.3,0.5)} +\psline[linewidth=4pt]{->}(4.0,2)(4.5,2) +\end{pspicture} + +\end{slide} + \end{document}