initial checkin of defense talk
[lectures/latex.git] / posic / talks / defense.tex
1 \pdfoutput=0
2 %\documentclass[landscape,semhelv,draft]{seminar}
3 \documentclass[landscape,semhelv]{seminar}
4
5 \usepackage{verbatim}
6 \usepackage[greek,german]{babel}
7 \usepackage[latin1]{inputenc}
8 \usepackage[T1]{fontenc}
9 \usepackage{amsmath}
10 \usepackage{stmaryrd}
11 \usepackage{latexsym}
12 \usepackage{ae}
13
14 \usepackage{calc}               % Simple computations with LaTeX variables
15 \usepackage{caption}            % Improved captions
16 \usepackage{fancybox}           % To have several backgrounds
17
18 \usepackage{fancyhdr}           % Headers and footers definitions
19 \usepackage{fancyvrb}           % Fancy verbatim environments
20 \usepackage{pstricks}           % PSTricks with the standard color package
21
22 \usepackage{pstricks}
23 \usepackage{pst-node}
24 \usepackage{pst-grad}
25
26 %\usepackage{epic}
27 %\usepackage{eepic}
28
29 \usepackage{layout}
30
31 \usepackage{graphicx}
32 \graphicspath{{../img/}}
33
34 \usepackage{miller}
35
36 \usepackage[setpagesize=false]{hyperref}
37
38 % units
39 \usepackage{units}
40
41 \usepackage{semcolor}
42 \usepackage{semlayer}           % Seminar overlays
43 \usepackage{slidesec}           % Seminar sections and list of slides
44
45 \input{seminar.bug}             % Official bugs corrections
46 \input{seminar.bg2}             % Unofficial bugs corrections
47
48 \articlemag{1}
49
50 \special{landscape}
51
52 % font
53 %\usepackage{cmbright}
54 %\renewcommand{\familydefault}{\sfdefault}
55 %\usepackage{mathptmx}
56
57 \usepackage{upgreek}
58
59 %\newrgbcolor{hred}{0.9 0.13 0.13}
60 %\newrgbcolor{hblue}{0.13 0.13 0.9}
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63
64 \begin{document}
65
66 \extraslideheight{10in}
67 \slideframe{plain}
68
69 \pagestyle{empty}
70
71 % specify width and height
72 \slidewidth 26.3cm 
73 \slideheight 19.9cm 
74
75 % margin
76 \def\slidetopmargin{-0.15cm}
77
78 \newcommand{\ham}{\mathcal{H}}
79 \newcommand{\pot}{\mathcal{V}}
80 \newcommand{\foo}{\mathcal{U}}
81 \newcommand{\vir}{\mathcal{W}}
82
83 % itemize level ii
84 \renewcommand\labelitemii{{\color{gray}$\bullet$}}
85
86 % nice phi
87 \renewcommand{\phi}{\varphi}
88
89 % roman letters
90 \newcommand{\RM}[1]{\MakeUppercase{\romannumeral #1{}}}
91
92 % colors
93 \newrgbcolor{si-yellow}{.6 .6 0}
94 \newrgbcolor{hb}{0.75 0.77 0.89}
95 \newrgbcolor{lbb}{0.75 0.8 0.88}
96 \newrgbcolor{hlbb}{0.825 0.88 0.968}
97 \newrgbcolor{lachs}{1.0 .93 .81}
98
99 % head
100 \newcommand{\headphd}{
101 \begin{pspicture}(0,0)(0,0)
102 \rput(6.0,0.2){\psframebox[fillstyle=gradient,gradbegin=hb,gradend=white,gradlines=1000,gradmidpoint=1,linestyle=none]{
103 \begin{minipage}{14cm}
104 \hfill
105 \vspace{0.7cm}
106 \end{minipage}
107 }}
108 \end{pspicture}
109 }
110
111 % shortcuts
112 \newcommand{\si}{Si$_{\text{i}}${}}
113 \newcommand{\ci}{C$_{\text{i}}${}}
114 \newcommand{\cs}{C$_{\text{sub}}${}}
115 \newcommand{\degc}[1]{\unit[#1]{$^{\circ}$C}{}}
116 \newcommand{\distn}[1]{\unit[#1]{nm}{}}
117 \newcommand{\dista}[1]{\unit[#1]{\AA}{}}
118 \newcommand{\perc}[1]{\unit[#1]{\%}{}}
119
120 % no vertical centering
121 %\centerslidesfalse
122
123 % layout check
124 %\layout
125 \begin{slide}
126 \center
127 {\Huge
128 E\\
129 F\\
130 G\\
131 A B C D E F G H G F E D C B A
132 G\\
133 F\\
134 E\\
135 }
136 \end{slide}
137
138 % topic
139
140 \begin{slide}
141 \begin{center}
142
143  \vspace{16pt}
144
145  {\LARGE\bf
146   Atomistic simulation study\\[0.2cm]
147   on silicon carbide precipitation\\[0.2cm]
148   in silicon
149  }
150
151  \vspace{48pt}
152
153  \textsc{Frank Zirkelbach}
154
155  \vspace{48pt}
156
157  Defense of doctor's thesis
158
159  \vspace{08pt}
160
161  Augsburg, 10. Jan. 2012
162
163 \end{center}
164 \end{slide}
165
166 % no vertical centering
167 \centerslidesfalse
168
169 % intro
170
171 % motivation / properties / applications of silicon carbide
172
173 \begin{slide}
174
175 \vspace*{1.8cm}
176
177 \small
178
179 \begin{pspicture}(0,0)(13.5,5)
180
181  \psframe*[linecolor=hb](-0.2,0)(12.9,5)
182
183  \pspolygon[linecolor=hlbb,fillcolor=hlbb,fillstyle=solid](5.2,1)(6.5,1)(6.5,3)(5.2,3)
184  \pspolygon[linecolor=hlbb,fillcolor=hlbb,fillstyle=solid](6.4,0.5)(7.7,2)(7.7,2)(6.4,3.5)
185
186  \rput[lt](0,4.6){\color{gray}PROPERTIES}
187
188  \rput[lt](0.3,4){wide band gap}
189  \rput[lt](0.3,3.5){high electric breakdown field}
190  \rput[lt](0.3,3){good electron mobility}
191  \rput[lt](0.3,2.5){high electron saturation drift velocity}
192  \rput[lt](0.3,2){high thermal conductivity}
193
194  \rput[lt](0.3,1.5){hard and mechanically stable}
195  \rput[lt](0.3,1){chemically inert}
196
197  \rput[lt](0.3,0.5){radiation hardness}
198
199  \rput[rt](12.7,4.6){\color{gray}APPLICATIONS}
200
201  \rput[rt](12.5,3.85){high-temperature, high power}
202  \rput[rt](12.5,3.5){and high-frequency}
203  \rput[rt](12.5,3.15){electronic and optoelectronic devices}
204
205  \rput[rt](12.5,2.35){material suitable for extreme conditions}
206  \rput[rt](12.5,2){microelectromechanical systems}
207  \rput[rt](12.5,1.65){abrasives, cutting tools, heating elements}
208
209  \rput[rt](12.5,0.85){first wall reactor material, detectors}
210  \rput[rt](12.5,0.5){and electronic devices for space}
211
212 \end{pspicture}
213
214 \begin{picture}(0,0)(5,-162)
215 \includegraphics[height=2.2cm]{3C_SiC_bs.eps}
216 \end{picture}
217 \begin{picture}(0,0)(-120,-162)
218 \includegraphics[height=2.2cm]{nasa_600c_led.eps}
219 \end{picture}
220 \begin{picture}(0,0)(-270,-162)
221 \includegraphics[height=2.2cm]{6h-sic_3c-sic.eps}
222 \end{picture}
223 %%%%
224 \begin{picture}(0,0)(10,65)
225 \includegraphics[height=2.8cm]{sic_switch.eps}
226 \end{picture}
227 %\begin{picture}(0,0)(-243,65)
228 \begin{picture}(0,0)(-110,65)
229 \includegraphics[height=2.8cm]{ise_99.eps}
230 \end{picture}
231 %\begin{picture}(0,0)(-135,65)
232 \begin{picture}(0,0)(-100,65)
233 \includegraphics[height=1.2cm]{infineon_schottky.eps}
234 \end{picture}
235 \begin{picture}(0,0)(-233,65)
236 \includegraphics[height=2.8cm]{solar_car.eps}
237 \end{picture}
238
239 \end{slide}
240
241 % motivation
242
243 \begin{slide}
244
245  {\large\bf
246   Polytypes of SiC\\[0.4cm]
247  }
248
249 \includegraphics[width=3.8cm]{cubic_hex.eps}\\
250 \begin{minipage}{1.9cm}
251 {\tiny cubic (twist)}
252 \end{minipage}
253 \begin{minipage}{2.9cm}
254 {\tiny hexagonal (no twist)}
255 \end{minipage}
256
257 \begin{picture}(0,0)(-150,0)
258  \includegraphics[width=7cm]{polytypes.eps}
259 \end{picture}
260
261 \vspace{0.6cm}
262
263 \footnotesize
264
265 \begin{tabular}{l c c c c c c}
266 \hline
267  & 3C-SiC & 4H-SiC & 6H-SiC & Si & GaN & Diamond\\
268 \hline
269 Hardness [Mohs] & \multicolumn{3}{c}{------ 9.6 ------}& 6.5 & - & 10 \\
270 Band gap [eV] & 2.36 & 3.23 & 3.03 & 1.12 & 3.39 & 5.5 \\
271 Break down field [$10^6$ V/cm] & 4 & 3 & 3.2 & 0.6 & 5 & 10 \\
272 Saturation drift velocity [$10^7$ cm/s] & 2.5 & 2.0 & 2.0 & 1 & 2.7 & 2.7 \\
273 Electron mobility [cm$^2$/Vs] & 800 & 900 & 400 & 1100 & 900 & 2200 \\
274 Hole mobility [cm$^2$/Vs] & 320 & 120 & 90 & 420 & 150 & 1600 \\
275 Thermal conductivity [W/cmK] & 5.0 & 4.9 & 4.9 & 1.5 & 1.3 & 22 \\
276 \hline
277 \end{tabular}
278
279 \begin{pspicture}(0,0)(0,0)
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281 \end{pspicture}
282 \begin{pspicture}(0,0)(0,0)
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284 \end{pspicture}
285 \begin{pspicture}(0,0)(0,0)
286 \psellipse[linecolor=red](10.45,0.45)(0.4,0.2)
287 \end{pspicture}
288
289 \end{slide}
290
291 % fabrication
292
293 \begin{slide}
294
295 \headphd
296  {\large\bf
297   Fabrication of silicon carbide
298  }
299
300  \small
301  
302  \vspace{2pt}
303
304 \begin{center}
305  {\color{gray}
306  \emph{Silicon carbide --- Born from the stars, perfected on earth.}
307  }
308 \end{center}
309
310 \vspace{2pt}
311
312 SiC thin films by MBE \& CVD
313 \begin{itemize}
314  \item Much progress achieved in homo/heteroepitaxial SiC thin film growth
315  \item \underline{Commercially available} semiconductor power devices based on
316        \underline{\foreignlanguage{greek}{a}-SiC}
317  \item Production of favored \underline{3C-SiC} material
318        \underline{less advanced}
319  \item Quality and size not yet sufficient
320 \end{itemize}
321 \begin{picture}(0,0)(-310,-20)
322   \includegraphics[width=2.0cm]{cree.eps}
323 \end{picture}
324
325 \vspace{-0.2cm}
326
327 Alternative approach:
328 Ion beam synthesis (IBS) of burried 3C-SiC layers in Si\hkl(1 0 0)
329
330 \vspace{0.2cm}
331
332 \scriptsize
333
334 \framebox{
335 \begin{minipage}{3.15cm}
336  \begin{center}
337 \includegraphics[width=3cm]{imp.eps}\\
338  {\tiny
339   Carbon implantation
340  }
341  \end{center}
342 \end{minipage}
343 \begin{minipage}{3.15cm}
344  \begin{center}
345 \includegraphics[width=3cm]{annealing.eps}\\
346  {\tiny
347  Postannealing at $>$ \degc{1200}
348  }
349  \end{center}
350 \end{minipage}
351 }
352 \begin{minipage}{5.5cm}
353  \includegraphics[width=5.8cm]{ibs_3c-sic.eps}\\[-0.2cm]
354  \begin{center}
355  {\tiny
356   XTEM: single crystalline 3C-SiC in Si\hkl(1 0 0)
357  }
358  \end{center}
359 \end{minipage}
360
361 \end{slide}
362
363 % contents
364
365 \begin{slide}
366
367 \headphd
368 {\large\bf
369  Outline
370 }
371
372  \begin{itemize}
373   \item Supposed precipitation mechanism of SiC in Si
374   \item Utilized simulation techniques
375         \begin{itemize}
376          \item Molecular dynamics (MD) simulations
377          \item Density functional theory (DFT) calculations
378         \end{itemize}
379   \item C and Si self-interstitial point defects in silicon
380   \item Silicon carbide precipitation simulations
381   \item Summary / Conclusion / Outlook
382  \end{itemize}
383
384 \end{slide}
385
386 \begin{slide}
387
388 \headphd
389 {\large\bf
390  Formation of epitaxial single crystalline 3C-SiC
391 }
392
393 \footnotesize
394
395 \vspace{0.2cm}
396
397 \begin{center}
398 \begin{itemize}
399  \item \underline{Implantation step 1}\\[0.1cm]
400         Almost stoichiometric dose | \unit[180]{keV} | \degc{500}\\
401         $\Rightarrow$ Epitaxial {\color{blue}3C-SiC} layer \&
402         {\color{blue}precipitates}
403  \item \underline{Implantation step 2}\\[0.1cm]
404         Little remaining dose | \unit[180]{keV} | \degc{250}\\
405         $\Rightarrow$
406         Destruction/Amorphization of precipitates at layer interface
407  \item \underline{Annealing}\\[0.1cm]
408        \unit[10]{h} at \degc{1250}\\
409        $\Rightarrow$ Homogeneous 3C-SiC layer with sharp interfaces
410 \end{itemize}
411 \end{center}
412
413 \begin{minipage}{7cm}
414 \includegraphics[width=7cm]{ibs_3c-sic.eps}
415 \end{minipage}
416 \begin{minipage}{5cm}
417 \begin{pspicture}(0,0)(0,0)
418 \rnode{box}{
419 \psframebox[fillstyle=solid,fillcolor=white,linecolor=blue,linestyle=solid]{
420 \begin{minipage}{5.3cm}
421  \begin{center}
422  {\color{blue}
423   3C-SiC precipitation\\
424   not yet fully understood
425  }
426  \end{center}
427  \vspace*{0.1cm}
428  \renewcommand\labelitemi{$\Rightarrow$}
429  Details of the SiC precipitation
430  \begin{itemize}
431   \item significant technological progress\\
432         in SiC thin film formation
433   \item perspectives for processes relying\\
434         upon prevention of SiC precipitation
435  \end{itemize}
436 \end{minipage}
437 }}
438 \rput(-6.8,5.4){\pnode{h0}}
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443 \end{minipage}
444
445 \end{slide}
446
447 \begin{slide}
448
449 \headphd
450 {\large\bf
451   Supposed precipitation mechanism of SiC in Si
452 }
453
454  \scriptsize
455
456  \vspace{0.1cm}
457
458  \framebox{
459  \begin{minipage}{3.6cm}
460  \begin{center}
461  Si \& SiC lattice structure\\[0.1cm]
462  \includegraphics[width=2.3cm]{sic_unit_cell.eps}
463  \end{center}
464 {\tiny
465  \begin{minipage}{1.7cm}
466 \underline{Silicon}\\
467 {\color{yellow}$\bullet$} Si | {\color{gray}$\bullet$} Si\\
468 $a=\unit[5.429]{\\A}$\\
469 $\rho^*_{\text{Si}}=\unit[100]{\%}$
470  \end{minipage}
471  \begin{minipage}{1.7cm}
472 \underline{Silicon carbide}\\
473 {\color{yellow}$\bullet$} Si | {\color{gray}$\bullet$} C\\
474 $a=\unit[4.359]{\\A}$\\
475 $\rho^*_{\text{Si}}=\unit[97]{\%}$
476  \end{minipage}
477 }
478  \end{minipage}
479  }
480  \hspace{0.1cm}
481  \begin{minipage}{4.1cm}
482  \begin{center}
483  \includegraphics[width=3.3cm]{tem_c-si-db.eps}
484  \end{center}
485  \end{minipage}
486  \hspace{0.1cm}
487  \begin{minipage}{4.0cm}
488  \begin{center}
489  \includegraphics[width=3.3cm]{tem_3c-sic.eps}
490  \end{center}
491  \end{minipage}
492
493  \vspace{0.1cm}
494
495  \begin{minipage}{4.0cm}
496  \begin{center}
497  C-Si dimers (dumbbells)\\[-0.1cm]
498  on Si interstitial sites
499  \end{center}
500  \end{minipage}
501  \hspace{0.1cm}
502  \begin{minipage}{4.1cm}
503  \begin{center}
504  Agglomeration of C-Si dumbbells\\[-0.1cm]
505  $\Rightarrow$ dark contrasts
506  \end{center}
507  \end{minipage}
508  \hspace{0.1cm}
509  \begin{minipage}{4.0cm}
510  \begin{center}
511  Precipitation of 3C-SiC in Si\\[-0.1cm]
512  $\Rightarrow$ Moir\'e fringes\\[-0.1cm]
513  \& release of Si self-interstitials
514  \end{center}
515  \end{minipage}
516
517  \vspace{0.1cm}
518
519  \begin{minipage}{4.0cm}
520  \begin{center}
521  \includegraphics[width=3.3cm]{sic_prec_seq_01.eps}
522  \end{center}
523  \end{minipage}
524  \hspace{0.1cm}
525  \begin{minipage}{4.1cm}
526  \begin{center}
527  \includegraphics[width=3.3cm]{sic_prec_seq_02.eps}
528  \end{center}
529  \end{minipage}
530  \hspace{0.1cm}
531  \begin{minipage}{4.0cm}
532  \begin{center}
533  \includegraphics[width=3.3cm]{sic_prec_seq_03.eps}
534  \end{center}
535  \end{minipage}
536
537 \begin{pspicture}(0,0)(0,0)
538 \psline[linewidth=2pt]{->}(8.3,2)(8.8,2)
539 \psellipse[linecolor=blue](11.1,6.0)(0.3,0.5)
540 \rput{-20}{\psellipse[linecolor=blue](3.1,8.2)(0.3,0.5)}
541 \psline[linewidth=2pt]{->}(3.9,2)(4.4,2)
542 \rput(11.8,0.3){\rnode{init}{\psframebox[fillstyle=solid,fillcolor=hb]{
543  $4a_{\text{Si}}=5a_{\text{SiC}}$
544  }}}
545 \rput(11.5,8){\rnode{init}{\psframebox[fillstyle=solid,fillcolor=hb]{
546 \hkl(h k l) planes match
547  }}}
548 \rput(8.5,6.2){\rnode{init}{\psframebox[fillstyle=solid,fillcolor=hb]{
549 r = \unit[2--4]{nm}
550  }}}
551 \end{pspicture}
552
553 \end{slide}
554
555 \begin{slide}
556
557 \headphd
558 {\large\bf
559  Supposed precipitation mechanism of SiC in Si
560 }
561
562  \scriptsize
563
564  \vspace{0.1cm}
565
566  \framebox{
567  \begin{minipage}{3.6cm}
568  \begin{center}
569  Si \& SiC lattice structure\\[0.1cm]
570  \includegraphics[width=2.3cm]{sic_unit_cell.eps}
571  \end{center}
572 {\tiny
573  \begin{minipage}{1.7cm}
574 \underline{Silicon}\\
575 {\color{yellow}$\bullet$} Si | {\color{gray}$\bullet$} Si\\
576 $a=\unit[5.429]{\\A}$\\
577 $\rho^*_{\text{Si}}=\unit[100]{\%}$
578  \end{minipage}
579  \begin{minipage}{1.7cm}
580 \underline{Silicon carbide}\\
581 {\color{yellow}$\bullet$} Si | {\color{gray}$\bullet$} C\\
582 $a=\unit[4.359]{\\A}$\\
583 $\rho^*_{\text{Si}}=\unit[97]{\%}$
584  \end{minipage}
585 }
586  \end{minipage}
587  }
588  \hspace{0.1cm}
589  \begin{minipage}{4.1cm}
590  \begin{center}
591  \includegraphics[width=3.3cm]{tem_c-si-db.eps}
592  \end{center}
593  \end{minipage}
594  \hspace{0.1cm}
595  \begin{minipage}{4.0cm}
596  \begin{center}
597  \includegraphics[width=3.3cm]{tem_3c-sic.eps}
598  \end{center}
599  \end{minipage}
600
601  \vspace{0.1cm}
602
603  \begin{minipage}{4.0cm}
604  \begin{center}
605  C-Si dimers (dumbbells)\\[-0.1cm]
606  on Si interstitial sites
607  \end{center}
608  \end{minipage}
609  \hspace{0.1cm}
610  \begin{minipage}{4.1cm}
611  \begin{center}
612  Agglomeration of C-Si dumbbells\\[-0.1cm]
613  $\Rightarrow$ dark contrasts
614  \end{center}
615  \end{minipage}
616  \hspace{0.1cm}
617  \begin{minipage}{4.0cm}
618  \begin{center}
619  Precipitation of 3C-SiC in Si\\[-0.1cm]
620  $\Rightarrow$ Moir\'e fringes\\[-0.1cm]
621  \& release of Si self-interstitials
622  \end{center}
623  \end{minipage}
624
625  \vspace{0.1cm}
626
627  \begin{minipage}{4.0cm}
628  \begin{center}
629  \includegraphics[width=3.3cm]{sic_prec_seq_01.eps}
630  \end{center}
631  \end{minipage}
632  \hspace{0.1cm}
633  \begin{minipage}{4.1cm}
634  \begin{center}
635  \includegraphics[width=3.3cm]{sic_prec_seq_02.eps}
636  \end{center}
637  \end{minipage}
638  \hspace{0.1cm}
639  \begin{minipage}{4.0cm}
640  \begin{center}
641  \includegraphics[width=3.3cm]{sic_prec_seq_03.eps}
642  \end{center}
643  \end{minipage}
644
645 \begin{pspicture}(0,0)(0,0)
646 \psline[linewidth=2pt]{->}(8.3,2)(8.8,2)
647 \psellipse[linecolor=blue](11.1,6.0)(0.3,0.5)
648 \rput{-20}{\psellipse[linecolor=blue](3.1,8.2)(0.3,0.5)}
649 \psline[linewidth=2pt]{->}(3.9,2)(4.4,2)
650 \rput(11.8,0.3){\rnode{init}{\psframebox[fillstyle=solid,fillcolor=hb]{
651  $4a_{\text{Si}}=5a_{\text{SiC}}$
652  }}}
653 \rput(11.5,8){\rnode{init}{\psframebox[fillstyle=solid,fillcolor=hb]{
654 \hkl(h k l) planes match
655  }}}
656 \rput(8.5,6.2){\rnode{init}{\psframebox[fillstyle=solid,fillcolor=hb]{
657 r = \unit[2--4]{nm}
658  }}}
659 % controversial view!
660 \rput(6.5,5.0){\psframebox[fillstyle=solid,opacity=0.5,fillcolor=black]{
661 \begin{minipage}{14cm}
662 \hfill
663 \vspace{12cm}
664 \end{minipage}
665 }}
666 \rput(6.5,5.3){\rnode{init}{\psframebox[fillstyle=solid,fillcolor=white,linewidth=0.1cm]{
667 \begin{minipage}{10cm}
668 \small
669 \vspace*{0.2cm}
670 \begin{center}
671 {\color{gray}\bf Controversial findings}
672 \end{center}
673 \begin{itemize}
674 \item High-temperature implantation {\tiny\color{gray}/Nejim~et~al./}
675  \begin{itemize}
676   \item C incorporated {\color{blue}substitutionally} on regular Si lattice sites
677   \item \si{} reacting with further C in cleared volume
678  \end{itemize}
679 \item Annealing behavior {\tiny\color{gray}/Serre~et~al./}
680  \begin{itemize}
681   \item Room temperature implantation $\rightarrow$ high C diffusion
682   \item Elevated temperature implantation $\rightarrow$ no C redistribution
683  \end{itemize}
684  $\Rightarrow$ mobile {\color{red}\ci} opposed to
685  stable {\color{blue}\cs{}} configurations
686 \item Strained silicon \& Si/SiC heterostructures
687       {\tiny\color{gray}/Strane~et~al./Guedj~et~al./}
688  \begin{itemize}
689   \item {\color{blue}Coherent} SiC precipitates (tensile strain)
690   \item Incoherent SiC (strain relaxation)
691  \end{itemize}
692 \end{itemize}
693 \vspace{0.1cm}
694 \begin{center}
695 {\Huge${\lightning}$} \hspace{0.3cm}
696 {\color{blue}\cs{}} --- vs --- {\color{red}\ci} \hspace{0.3cm}
697 {\Huge${\lightning}$}
698 \end{center}
699 \vspace{0.2cm}
700 \end{minipage}
701  }}}
702 \end{pspicture}
703
704 \end{slide}
705
706 \begin{slide}
707
708 \headphd
709 {\large\bf
710  Utilized computational methods
711 }
712
713 \vspace{0.3cm}
714
715 \small
716
717 {\bf Molecular dynamics (MD)}\\[0.1cm]
718 \scriptsize
719 \begin{tabular}{| p{4.5cm} | p{7.5cm} |}
720 \hline
721 System of $N$ particles &
722 $N=5832\pm 1$ (Defects), $N=238328+6000$ (Precipitation)\\
723 Phase space propagation &
724 Velocity Verlet | timestep: \unit[1]{fs} \\
725 Analytical interaction potential &
726 Tersoff-like {\color{red}short-range}, {\color{blue}bond order} potential
727 (Erhart/Albe)
728 $\displaystyle
729 E = \frac{1}{2} \sum_{i \neq j} \pot_{ij}, \quad
730     \pot_{ij} = {\color{red}f_C(r_{ij})}
731     \left[ f_R(r_{ij}) + {\color{blue}b_{ij}} f_A(r_{ij}) \right]
732 $\\
733 Observables: time/ensemble averages &
734 NpT (isothermal-isobaric) | Berendsen thermostat/barostat\\
735 \hline
736 \end{tabular}
737
738 \small
739
740 \vspace{0.3cm}
741
742 {\bf Density functional theory (DFT)}
743
744 \scriptsize
745
746 \begin{minipage}[t]{6cm}
747 \begin{itemize}
748  \item Hohenberg-Kohn theorem:\\
749        $\Psi_0(r_1,r_2,\ldots,r_N)=\Psi[n_0(r)]$, $E_0=E[n_0]$
750  \item Kohn-Sham approach:\\
751        Single-particle effective theory
752 \end{itemize}
753 \hrule
754 \begin{itemize}
755 \item Code: \textsc{vasp}
756 \item Plane wave basis set
757 %$\displaystyle
758 %\Phi_i=\sum_{|G+k|<G_{\text{cut}}} c_{i,k+G} \exp{\left(i(k+G)r\right)}
759 %$\\
760 %$\displaystyle
761 %E_{\text{cut}}=\frac{\hbar^2}{2m}G^2_{\text{cut}}=\unit[300]{eV}
762 %$
763 \item Ultrasoft pseudopotential
764 \item Exchange \& correlation: GGA
765 \item Brillouin zone sampling: $\Gamma$-point
766 \item Supercell: $N=216\pm2$
767 \end{itemize}
768 \end{minipage}
769 \begin{minipage}{6cm}
770 \begin{pspicture}(0,0)(0,0)
771 \pscircle[fillcolor=yellow,fillstyle=solid,linestyle=none](3.5,-2.0){2.5}
772 \rput(2.7,-0.7){\psframebox[fillstyle=solid,opacity=0.8,fillcolor=white]{
773 $\displaystyle
774 \left[ -\frac{\hbar^2}{2m}\nabla^2 + V_{\text{eff}}(r) - \epsilon_i \right] \Phi_i(r) = 0
775 $
776 }}
777 \rput(5.2,-2.0){\psframebox[fillstyle=solid,opacity=0.8,fillcolor=white]{
778 $\displaystyle
779 n(r)=\sum_i^N|\Phi_i(r)|^2
780 $
781 }}
782 \rput(3.0,-4.5){\psframebox[fillstyle=solid,opacity=0.8,fillcolor=white]{
783 $\displaystyle
784 V_{\text{eff}}(r)=V_{\text{ext}}(r)+\int\frac{e^2 n(r')}{|r-r'|}d^3r'
785                  +V_{\text{XC}}[n(r)]
786 $
787 }}
788 \psarcn[linewidth=0.07cm,linestyle=dashed]{->}(3.5,-2.0){2.5}{130}{15}
789 \psarcn[linewidth=0.07cm,linestyle=dashed]{->}(3.5,-2.0){2.5}{230}{165}
790 \psarcn[linewidth=0.07cm,linestyle=dashed]{->}(3.5,-2.0){2.5}{345}{310}
791
792 \end{pspicture}
793 \end{minipage}
794
795 \end{slide}
796
797 \begin{slide}
798
799 \headphd
800  {\large\bf
801   Point defects \& defect migration
802  }
803
804  \small
805
806  \vspace{0.2cm}
807
808 \begin{minipage}[b]{7.5cm}
809 {\bf Defect structure}\\
810   \begin{pspicture}(0,0)(7,4.4)
811   \rput(3.5,3.2){\rnode{init}{\psframebox[fillstyle=solid,fillcolor=hb]{
812    \parbox{7cm}{
813    \begin{itemize}
814     \item Creation of c-Si simulation volume
815     \item Periodic boundary conditions
816     \item $T=0\text{ K}$, $p=0\text{ bar}$
817    \end{itemize}
818   }}}}
819 \rput(3.5,1.3){\rnode{insert}{\psframebox{
820  \parbox{7cm}{
821   \begin{center}
822   Insertion of interstitial C/Si atoms
823   \end{center}
824   }}}}
825   \rput(3.5,0.2){\rnode{cool}{\psframebox[fillstyle=solid,fillcolor=lbb]{
826    \parbox{7cm}{
827    \begin{center}
828    Relaxation / structural energy minimization
829    \end{center}
830   }}}}
831   \ncline[]{->}{init}{insert}
832   \ncline[]{->}{insert}{cool}
833  \end{pspicture}
834 \end{minipage}
835 \begin{minipage}[b]{4.5cm}
836 \begin{center}
837 \includegraphics[width=3.8cm]{unit_cell_e.eps}\\
838 \end{center}
839 \begin{minipage}{2.21cm}
840 {\scriptsize
841 {\color{red}$\bullet$} Tetrahedral\\[-0.1cm]
842 {\color{green}$\bullet$} Hexagonal\\[-0.1cm]
843 {\color{yellow}$\bullet$} \hkl<1 0 0> DB
844 }
845 \end{minipage}
846 \begin{minipage}{2.21cm}
847 {\scriptsize
848 {\color{magenta}$\bullet$} \hkl<1 1 0> DB\\[-0.1cm]
849 {\color{cyan}$\bullet$} Bond-centered\\[-0.1cm]
850 {\color{black}$\bullet$} Vac. / Sub.
851 }
852 \end{minipage}
853 \end{minipage}
854
855 \vspace{0.2cm}
856
857 \begin{minipage}[b]{6cm}
858 {\bf Defect formation energy}\\
859 \framebox{
860 $E_{\text{f}}=E-\sum_i N_i\mu_i$}\\[0.1cm]
861 Particle reservoir: Si \& SiC\\[0.2cm]
862 {\bf Binding energy}\\
863 \framebox{
864 $
865 E_{\text{b}}=
866 E_{\text{f}}^{\text{comb}}-
867 E_{\text{f}}^{1^{\text{st}}}-
868 E_{\text{f}}^{2^{\text{nd}}}
869 $
870 }\\[0.1cm]
871 \footnotesize
872 $E_{\text{b}}<0$: energetically favorable configuration\\
873 $E_{\text{b}}\rightarrow 0$: non-interacting, isolated defects\\
874 \end{minipage}
875 \begin{minipage}[b]{6cm}
876 {\bf Migration barrier}
877 \footnotesize
878 \begin{itemize}
879  \item Displace diffusing atom
880  \item Constrain relaxation of (diffusing) atoms
881  \item Record configurational energy
882 \end{itemize}
883 \begin{picture}(0,0)(-60,-33)
884 \includegraphics[width=4.5cm]{crt_mod.eps}
885 \end{picture}
886 \end{minipage}
887
888 \end{slide}
889
890 \begin{slide}
891
892 \footnotesize
893
894 \headphd
895 {\large\bf
896  Si self-interstitial point defects in silicon\\[0.1cm]
897 }
898
899 \begin{center}
900 \begin{tabular}{l c c c c c}
901 \hline
902  $E_{\text{f}}$ [eV] & \hkl<1 1 0> DB & H & T & \hkl<1 0 0> DB & V \\
903 \hline
904  \textsc{vasp} & \underline{3.39} & 3.42 & 3.77 & 4.41 & 3.63 \\
905  Erhart/Albe & 4.39 & 4.48$^*$ & \underline{3.40} & 5.42 & 3.13 \\
906 \hline
907 \end{tabular}\\[0.4cm]
908 \end{center}
909
910 \begin{minipage}{3cm}
911 \begin{center}
912 \underline{Vacancy}\\
913 \includegraphics[width=2.8cm]{si_pd_albe/vac.eps}
914 \end{center}
915 \end{minipage}
916 \begin{minipage}{3cm}
917 \begin{center}
918 \underline{\hkl<1 1 0> DB}\\
919 \includegraphics[width=2.8cm]{si_pd_albe/110_bonds.eps}
920 \end{center}
921 \end{minipage}
922 \begin{minipage}{3cm}
923 \begin{center}
924 \underline{\hkl<1 0 0> DB}\\
925 \includegraphics[width=2.8cm]{si_pd_albe/100_bonds.eps}
926 \end{center}
927 \end{minipage}
928 \begin{minipage}{3cm}
929 \begin{center}
930 \underline{Tetrahedral}\\
931 \includegraphics[width=2.8cm]{si_pd_albe/tet_bonds.eps}
932 \end{center}
933 \end{minipage}\\
934
935 \underline{Hexagonal} \hspace{2pt}
936 \href{../video/si_self_int_hexa.avi}{$\rhd$}\\[0.1cm]
937 \framebox{
938 \begin{minipage}{2.7cm}
939 $E_{\text{f}}^*=4.48\text{ eV}$\\
940 \includegraphics[width=2.7cm]{si_pd_albe/hex_a_bonds.eps}
941 \end{minipage}
942 \begin{minipage}{0.4cm}
943 \begin{center}
944 $\Rightarrow$
945 \end{center}
946 \end{minipage}
947 \begin{minipage}{2.7cm}
948 $E_{\text{f}}=3.96\text{ eV}$\\
949 \includegraphics[width=2.8cm]{si_pd_albe/hex_bonds.eps}
950 \end{minipage}
951 }
952 \begin{minipage}{5.5cm}
953 \begin{center}
954 {\tiny nearly T $\rightarrow$ T}\\
955 \end{center}
956 \includegraphics[width=6.0cm]{nhex_tet.ps}
957 \end{minipage}
958
959 \end{slide}
960
961 \begin{slide}
962
963 \footnotesize
964
965 \headphd
966 {\large\bf
967  C interstitial point defects in silicon\\
968 }
969
970 \begin{tabular}{l c c c c c c r}
971 \hline
972  $E_{\text{f}}$ [eV] & T & H & \hkl<1 0 0> DB & \hkl<1 1 0> DB & S & B &
973  {\color{black} \cs{} \& \si}\\
974 \hline
975  \textsc{vasp} & unstable & unstable & \underline{3.72} & 4.16 & 1.95 & 4.66 & {\color{green}4.17}\\
976  Erhart/Albe & 6.09 & 9.05$^*$ & \underline{3.88} & 5.18 & {\color{red}0.75} & 5.59$^*$ & {\color{green}4.43} \\
977 \hline
978 \end{tabular}\\[0.1cm]
979
980 \framebox{
981 \begin{minipage}{2.8cm}
982 \underline{Hexagonal} \hspace{2pt}
983 \href{../video/c_in_si_int_hexa.avi}{$\rhd$}\\
984 $E_{\text{f}}^*=9.05\text{ eV}$\\
985 \includegraphics[width=2.8cm]{c_pd_albe/hex_bonds.eps}
986 \end{minipage}
987 \begin{minipage}{0.4cm}
988 \begin{center}
989 $\Rightarrow$
990 \end{center}
991 \end{minipage}
992 \begin{minipage}{2.8cm}
993 \underline{\hkl<1 0 0>}\\
994 $E_{\text{f}}=3.88\text{ eV}$\\
995 \includegraphics[width=2.8cm]{c_pd_albe/100_bonds.eps}
996 \end{minipage}
997 }
998 \begin{minipage}{1.4cm}
999 \hfill
1000 \end{minipage}
1001 \begin{minipage}{3.0cm}
1002 \begin{flushright}
1003 \underline{Tetrahedral}\\
1004 \includegraphics[width=3.0cm]{c_pd_albe/tet_bonds.eps}
1005 \end{flushright}
1006 \end{minipage}
1007
1008 \framebox{
1009 \begin{minipage}{2.8cm}
1010 \underline{Bond-centered}\\
1011 $E_{\text{f}}^*=5.59\text{ eV}$\\
1012 \includegraphics[width=2.8cm]{c_pd_albe/bc_bonds.eps}
1013 \end{minipage}
1014 \begin{minipage}{0.4cm}
1015 \begin{center}
1016 $\Rightarrow$
1017 \end{center}
1018 \end{minipage}
1019 \begin{minipage}{2.8cm}
1020 \underline{\hkl<1 1 0> dumbbell}\\
1021 $E_{\text{f}}=5.18\text{ eV}$\\
1022 \includegraphics[width=2.8cm]{c_pd_albe/110_bonds.eps}
1023 \end{minipage}
1024 }
1025 \begin{minipage}{1.4cm}
1026 \hfill
1027 \end{minipage}
1028 \begin{minipage}{3.0cm}
1029 \begin{flushright}
1030 \underline{Substitutional}\\
1031 \includegraphics[width=3.0cm]{c_pd_albe/sub_bonds.eps}
1032 \end{flushright}
1033 \end{minipage}
1034
1035 \end{slide}
1036
1037 \begin{slide}
1038
1039 \headphd
1040 {\large\bf\boldmath
1041  C-Si dimer \& bond-centered interstitial configuration
1042 }
1043
1044 \footnotesize
1045
1046 \vspace{0.1cm}
1047
1048 \begin{minipage}[t]{4.1cm}
1049 {\bf\boldmath C \hkl<1 0 0> DB interstitial}\\[0.1cm]
1050 \begin{minipage}{2.0cm}
1051 \begin{center}
1052 \underline{Erhart/Albe}
1053 \includegraphics[width=2.0cm]{c_pd_albe/100_cmp.eps}
1054 \end{center}
1055 \end{minipage}
1056 \begin{minipage}{2.0cm}
1057 \begin{center}
1058 \underline{\textsc{vasp}}
1059 \includegraphics[width=2.0cm]{c_pd_vasp/100_cmp.eps}
1060 \end{center}
1061 \end{minipage}\\[0.2cm]
1062 Si-C-Si bond angle $\rightarrow$ \unit[180]{$^{\circ}$}\\
1063 $\Rightarrow$ $sp$ hybridization\\[0.1cm]
1064 Si-Si-Si bond angle $\rightarrow$ \unit[120]{$^{\circ}$}\\
1065 $\Rightarrow$ $sp^2$ hybridization
1066 \begin{center}
1067 \includegraphics[width=3.4cm]{c_pd_vasp/eden.eps}\\[-0.1cm]
1068 {\tiny Charge density isosurface}
1069 \end{center}
1070 \end{minipage}
1071 \begin{minipage}{0.2cm}
1072 \hfill
1073 \end{minipage}
1074 \begin{minipage}[t]{8.1cm}
1075 \begin{flushright}
1076 {\bf Bond-centered interstitial}\\[0.1cm]
1077 \begin{minipage}{4.4cm}
1078 %\scriptsize
1079 \begin{itemize}
1080  \item Linear Si-C-Si bond
1081  \item Si: one C \& 3 Si neighbours
1082  \item Spin polarized calculations
1083  \item No saddle point!\\
1084        Real local minimum!
1085 \end{itemize}
1086 \end{minipage}
1087 \begin{minipage}{2.7cm}
1088 %\includegraphics[width=2.8cm]{c_pd_vasp/bc_2333.eps}\\
1089 \vspace{0.2cm}
1090 \includegraphics[width=2.8cm]{c_pd_albe/bc_bonds.eps}\\
1091 \end{minipage}
1092
1093 \framebox{
1094  \tiny
1095  \begin{minipage}[t]{6.5cm}
1096   \begin{minipage}[t]{1.2cm}
1097   {\color{red}Si}\\
1098   {\tiny sp$^3$}\\[0.8cm]
1099   \underline{${\color{black}\uparrow}$}
1100   \underline{${\color{black}\uparrow}$}
1101   \underline{${\color{black}\uparrow}$}
1102   \underline{${\color{red}\uparrow}$}\\
1103   sp$^3$
1104   \end{minipage}
1105   \begin{minipage}[t]{1.4cm}
1106   \begin{center}
1107   {\color{red}M}{\color{blue}O}\\[0.8cm]
1108   \underline{${\color{blue}\uparrow}{\color{white}\downarrow}$}\\
1109   $\sigma_{\text{ab}}$\\[0.5cm]
1110   \underline{${\color{red}\uparrow}{\color{blue}\downarrow}$}\\
1111   $\sigma_{\text{b}}$
1112   \end{center}
1113   \end{minipage}
1114   \begin{minipage}[t]{1.0cm}
1115   \begin{center}
1116   {\color{blue}C}\\
1117   {\tiny sp}\\[0.2cm]
1118   \underline{${\color{white}\uparrow\uparrow}$}
1119   \underline{${\color{white}\uparrow\uparrow}$}\\
1120   2p\\[0.4cm]
1121   \underline{${\color{blue}\uparrow}{\color{blue}\downarrow}$}
1122   \underline{${\color{blue}\uparrow}{\color{blue}\downarrow}$}\\
1123   sp
1124   \end{center}
1125   \end{minipage}
1126   \begin{minipage}[t]{1.4cm}
1127   \begin{center}
1128   {\color{blue}M}{\color{green}O}\\[0.8cm]
1129   \underline{${\color{blue}\uparrow}{\color{white}\downarrow}$}\\
1130   $\sigma_{\text{ab}}$\\[0.5cm]
1131   \underline{${\color{green}\uparrow}{\color{blue}\downarrow}$}\\
1132   $\sigma_{\text{b}}$
1133   \end{center}
1134   \end{minipage}
1135   \begin{minipage}[t]{1.2cm}
1136   \begin{flushright}
1137   {\color{green}Si}\\
1138   {\tiny sp$^3$}\\[0.8cm]
1139   \underline{${\color{green}\uparrow}$}
1140   \underline{${\color{black}\uparrow}$}
1141   \underline{${\color{black}\uparrow}$}
1142   \underline{${\color{black}\uparrow}$}\\
1143   sp$^3$
1144   \end{flushright}
1145   \end{minipage}
1146  \end{minipage}
1147 }\\[0.4cm]
1148
1149 %\framebox{
1150 \begin{minipage}{3.0cm}
1151 %\scriptsize
1152 \underline{Charge density}\\
1153 {\color{gray}$\bullet$} Spin up\\
1154 {\color{green}$\bullet$} Spin down\\
1155 {\color{blue}$\bullet$} Resulting spin up\\
1156 {\color{yellow}$\bullet$} Si atoms\\
1157 {\color{red}$\bullet$} C atom
1158 \end{minipage}
1159 \begin{minipage}{3.6cm}
1160 \includegraphics[width=3.8cm]{c_100_mig_vasp/im_spin_diff.eps}
1161 \end{minipage}
1162 %}
1163
1164 \end{flushright}
1165
1166 \end{minipage}
1167 \begin{pspicture}(0,0)(0,0)
1168 \psline[linecolor=gray,linewidth=0.05cm](-7.8,-8.7)(-7.8,0)
1169 \end{pspicture}
1170
1171 \end{slide}
1172
1173 \begin{slide}
1174
1175 \headphd
1176 {\large\bf\boldmath
1177  C interstitial migration --- ab initio
1178 }
1179
1180 \scriptsize
1181
1182 \vspace{0.1cm}
1183
1184 \begin{minipage}{6.8cm}
1185 \framebox{\hkl[0 0 -1] $\rightarrow$ \hkl[0 0 1]}\\
1186 \begin{minipage}{2.0cm}
1187 \includegraphics[width=2.0cm]{c_pd_vasp/100_2333.eps}
1188 \end{minipage}
1189 \begin{minipage}{0.2cm}
1190 $\rightarrow$
1191 \end{minipage}
1192 \begin{minipage}{2.0cm}
1193 \includegraphics[width=2.0cm]{c_pd_vasp/bc_2333.eps}
1194 \end{minipage}
1195 \begin{minipage}{0.2cm}
1196 $\rightarrow$
1197 \end{minipage}
1198 \begin{minipage}{2.0cm}
1199 \includegraphics[width=2.0cm]{c_pd_vasp/100_next_2333.eps}
1200 \end{minipage}\\[0.1cm]
1201 Spin polarization\\
1202 $\Rightarrow$ BC configuration constitutes local minimum\\
1203 $\Rightarrow$ Migration barrier to reach BC | $\Delta E=\unit[1.2]{eV}$
1204 \end{minipage}
1205 \begin{minipage}{5.4cm}
1206 \includegraphics[width=6.0cm]{im_00-1_nosym_sp_fullct_thesis_vasp_s.ps}
1207 \end{minipage}\\[0.2cm]
1208 %\hrule
1209 %
1210 \begin{minipage}{6.8cm}
1211 \framebox{\hkl[0 0 -1] $\rightarrow$ \hkl[0 -1 0]}\\
1212 \begin{minipage}{2.0cm}
1213 \includegraphics[width=2.0cm]{c_pd_vasp/100_2333.eps}
1214 \end{minipage}
1215 \begin{minipage}{0.2cm}
1216 $\rightarrow$
1217 \end{minipage}
1218 \begin{minipage}{2.0cm}
1219 \includegraphics[width=2.0cm]{c_pd_vasp/00-1-0-10_2333.eps}
1220 \end{minipage}
1221 \begin{minipage}{0.2cm}
1222 $\rightarrow$
1223 \end{minipage}
1224 \begin{minipage}{2.0cm}
1225 \includegraphics[width=2.0cm]{c_pd_vasp/0-10_2333.eps}
1226 \end{minipage}\\[0.1cm]
1227 $\Delta E=\unit[0.9]{eV}$ | Experimental values: \unit[0.70--0.87]{eV}\\
1228 $\Rightarrow$ {\color{red}Migration mechanism identified!}\\
1229 Note: Change in orientation
1230 \end{minipage}
1231 \begin{minipage}{5.4cm}
1232 \includegraphics[width=6.0cm]{00-1_0-10_vasp_s.ps}
1233 \end{minipage}\\[0.1cm]
1234 %
1235 \begin{center}
1236 Reorientation pathway composed of two consecutive processes of the above type
1237 \end{center}
1238
1239 \end{slide}
1240
1241 \begin{slide}
1242
1243 \headphd
1244 {\large\bf\boldmath
1245  C interstitial migration --- analytical potential
1246 }
1247
1248 \scriptsize
1249
1250 \vspace{0.3cm}
1251
1252 \begin{minipage}[t]{6.0cm}
1253 {\bf\boldmath BC to \hkl[0 0 -1] transition}\\[0.2cm]
1254 \includegraphics[width=6.0cm]{bc_00-1_albe_s.ps}\\
1255 \begin{itemize}
1256  \item Lowermost migration barrier
1257  \item $\Delta E \approx \unit[2.2]{eV}$
1258  \item 2.4 times higher than ab initio result
1259  \item Different pathway
1260 \end{itemize}
1261 \end{minipage}
1262 \begin{minipage}[t]{0.2cm}
1263 \hfill
1264 \end{minipage}
1265 \begin{minipage}[t]{6.0cm}
1266 {\bf\boldmath Transition involving a \hkl<1 1 0> configuration}
1267 \vspace{0.1cm}
1268 \begin{itemize}
1269  \item Bond-centered configuration unstable\\
1270        $\rightarrow$ \ci{} \hkl<1 1 0> dumbbell
1271  \item Minima of the \hkl[0 0 -1] to \hkl[0 -1 0] transition\\
1272        $\rightarrow$ \ci{} \hkl<1 1 0> DB
1273 \end{itemize}
1274 \vspace{0.1cm}
1275 \includegraphics[width=6.0cm]{00-1_110_0-10_mig_albe.ps}
1276 \begin{itemize}
1277  \item $\Delta E \approx \unit[2.2]{eV} \text{ \& } \unit[0.9]{eV}$
1278  \item 2.4 -- 3.4 times higher than ab initio result
1279  \item After all: Change of the DB orientation
1280 \end{itemize}
1281 \end{minipage}
1282
1283 \vspace{0.5cm}
1284 \begin{center}
1285 {\color{red}\bf Drastically overestimated diffusion barrier}
1286 \end{center}
1287
1288 \begin{pspicture}(0,0)(0,0)
1289 \psline[linewidth=0.05cm,linecolor=gray](6.1,1.0)(6.1,9.3)
1290 \end{pspicture}
1291
1292 \end{slide}
1293
1294 \begin{slide}
1295
1296 \headphd
1297 {\large\bf\boldmath
1298  Defect combinations
1299 }
1300
1301 \footnotesize
1302
1303 \vspace{0.3cm}
1304
1305 \begin{minipage}{9cm}
1306 {\bf
1307  Summary of combinations}\\[0.1cm]
1308 {\scriptsize
1309 \begin{tabular}{l c c c c c c}
1310 \hline
1311  $E_{\text{b}}$ [eV] & 1 & 2 & 3 & 4 & 5 & R\\
1312  \hline
1313  \hkl[0 0 -1] & {\color{red}-0.08} & -1.15 & {\color{red}-0.08} & 0.04 & -1.66 & -0.19\\
1314  \hkl[0 0 1] & 0.34 & 0.004 & -2.05 & 0.26 & -1.53 & -0.19\\
1315  \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}\\
1316  \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}\\
1317  \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}\\
1318  \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}\\
1319  \hline
1320  C$_{\text{sub}}$ & 0.26 & -0.51 & -0.93 & -0.15 & 0.49 & -0.05\\
1321  Vacancy & -5.39 ($\rightarrow$ C$_{\text{sub}}$) & -0.59 & -3.14 & -0.54 & -0.50 & -0.31\\
1322 \hline
1323 \end{tabular}
1324 }
1325 \vspace{0.2cm}
1326 \begin{center}
1327 {\color{blue}
1328  $E_{\text{b}}$ explainable by stress compensation / increase
1329 }
1330 \end{center}
1331 \end{minipage}
1332 \begin{minipage}{3cm}
1333 \includegraphics[width=3.5cm]{comb_pos.eps}
1334 \end{minipage}
1335
1336 \vspace{0.2cm}
1337
1338 {\bf\boldmath Combinations of \hkl<1 0 0>-type interstitials}\\[0.2cm]
1339 \begin{minipage}[t]{3.2cm}
1340 \underline{\hkl[1 0 0] at position 1}\\[0.1cm]
1341 \includegraphics[width=2.8cm]{00-1dc/2-25.eps}
1342 \end{minipage}
1343 \begin{minipage}[t]{3.0cm}
1344 \underline{\hkl[0 -1 0] at position 1}\\[0.1cm]
1345 \includegraphics[width=2.8cm]{00-1dc/2-39.eps}
1346 \end{minipage}
1347 \begin{minipage}[t]{6.1cm}
1348 \vspace{0.7cm}
1349 \begin{itemize}
1350  \item \ci{} agglomeration energetically favorable
1351  \item Most favorable: C clustering\\
1352        {\color{red}However \ldots}\\
1353         \ldots high migration barrier ($>4\,\text{eV}$)\\
1354         \ldots entropy:
1355         $4\times{\color{cyan}[-2.25]}$ versus
1356         $2\times{\color{orange}[-2.39]}$
1357 \end{itemize}
1358 \begin{center}
1359 {\color{blue}\ci{} agglomeration / no C clustering}
1360 \end{center}
1361 \end{minipage}
1362
1363 \end{slide}
1364
1365 \begin{slide}
1366
1367 \headphd
1368 {\large\bf\boldmath
1369  Defect combinations
1370 }
1371
1372 \footnotesize
1373
1374 \vspace{0.3cm}
1375
1376 \begin{minipage}{9cm}
1377 {\bf
1378  Summary of combinations}\\[0.1cm]
1379 {\scriptsize
1380 \begin{tabular}{l c c c c c c}
1381 \hline
1382  $E_{\text{b}}$ [eV] & 1 & 2 & 3 & 4 & 5 & R\\
1383  \hline
1384  \hkl[0 0 -1] & {\color{red}-0.08} & -1.15 & {\color{red}-0.08} & 0.04 & -1.66 & -0.19\\
1385  \hkl[0 0 1] & 0.34 & 0.004 & -2.05 & 0.26 & -1.53 & -0.19\\
1386  \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}\\
1387  \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}\\
1388  \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}\\
1389  \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}\\
1390  \hline
1391  C$_{\text{sub}}$ & 0.26 & -0.51 & -0.93 & -0.15 & 0.49 & -0.05\\
1392  Vacancy & -5.39 ($\rightarrow$ C$_{\text{sub}}$) & -0.59 & -3.14 & -0.54 & -0.50 & -0.31\\
1393 \hline
1394 \end{tabular}
1395 }
1396 \vspace{0.2cm}
1397 \begin{center}
1398 {\color{blue}
1399  $E_{\text{b}}$ explainable by stress compensation / increase
1400 }
1401 \end{center}
1402 \end{minipage}
1403 \begin{minipage}{3cm}
1404 \includegraphics[width=3.5cm]{comb_pos.eps}
1405 \end{minipage}
1406
1407 \vspace{0.2cm}
1408
1409 {\bf\boldmath Combinations of \hkl<1 0 0>-type interstitials}\\[0.2cm]
1410 \begin{minipage}[t]{3.2cm}
1411 \underline{\hkl[1 0 0] at position 1}\\[0.1cm]
1412 \includegraphics[width=2.8cm]{00-1dc/2-25.eps}
1413 \end{minipage}
1414 \begin{minipage}[t]{3.0cm}
1415 \underline{\hkl[0 -1 0] at position 1}\\[0.1cm]
1416 \includegraphics[width=2.8cm]{00-1dc/2-39.eps}
1417 \end{minipage}
1418 \begin{minipage}[t]{6.1cm}
1419 \vspace{0.7cm}
1420 \begin{itemize}
1421  \item \ci{} agglomeration energetically favorable
1422  \item Most favorable: C clustering\\
1423        {\color{red}However \ldots}\\
1424         \ldots high migration barrier ($>4\,\text{eV}$)\\
1425         \ldots entropy:
1426         $4\times{\color{cyan}[-2.25]}$ versus
1427         $2\times{\color{orange}[-2.39]}$
1428 \end{itemize}
1429 \begin{center}
1430 {\color{blue}\ci{} agglomeration / no C clustering}
1431 \end{center}
1432 \end{minipage}
1433
1434 % insert graph ...
1435 \begin{pspicture}(0,0)(0,0)
1436 \rput(6.5,5.0){\psframebox[fillstyle=solid,opacity=0.5,fillcolor=black]{
1437 \begin{minipage}{14cm}
1438 \hfill
1439 \vspace{12cm}
1440 \end{minipage}
1441 }}
1442 \rput(6.5,5.3){\rnode{init}{\psframebox[fillstyle=solid,fillcolor=white,linewidth=0.1cm]{
1443 \begin{minipage}{8cm}
1444 \begin{center}
1445 \vspace{0.2cm}
1446 \scriptsize
1447 Interaction along \hkl[1 1 0]
1448 \includegraphics[width=7cm]{db_along_110_cc.ps}
1449 \end{center}
1450 \end{minipage}
1451 }}}
1452 \end{pspicture}
1453
1454 \end{slide}
1455
1456 \begin{slide}
1457
1458 \headphd
1459 {\large\bf
1460  Defect combinations of C-Si dimers and vacancies
1461 }
1462 \footnotesize
1463
1464 \vspace{0.2cm}
1465
1466 \begin{minipage}[b]{2.6cm}
1467 \begin{flushleft}
1468 \underline{V at 2: $E_{\text{b}}=-0.59\text{ eV}$}\\[0.1cm]
1469 \includegraphics[width=2.5cm]{00-1dc/0-59.eps}
1470 \end{flushleft}
1471 \end{minipage}
1472 \begin{minipage}[b]{7cm}
1473 \hfill
1474 \end{minipage}
1475 \begin{minipage}[b]{2.6cm}
1476 \begin{flushright}
1477 \underline{V at 3, $E_{\text{b}}=-3.14\text{ eV}$}\\[0.1cm]
1478 \includegraphics[width=2.5cm]{00-1dc/3-14.eps}
1479 \end{flushright}
1480 \end{minipage}\\[0.2cm]
1481
1482 \begin{minipage}{6.5cm}
1483 \includegraphics[width=6.0cm]{059-539.ps}
1484 \end{minipage}
1485 \begin{minipage}{5.7cm}
1486 \includegraphics[width=6.0cm]{314-539.ps}
1487 \end{minipage}
1488
1489 \begin{pspicture}(0,0)(0,0)
1490 \psline[linewidth=0.05cm,linecolor=gray](6.3,9.0)(6.3,0)
1491
1492 \rput(6.3,7.0){\rnode{init}{\psframebox[fillstyle=solid,fillcolor=white,linewidth=0.05cm,linecolor=gray]{
1493 \begin{minipage}{6.5cm}
1494 \begin{center}
1495 IBS: Impinging C creates V \& far away \si\\[0.3cm]
1496 Low migration barrier towards C$_{\text{sub}}$\\
1497 \&\\
1498 High barrier for reverse process\\[0.3cm]
1499 {\color{blue}
1500 High probability of stable C$_{\text{sub}}$ configuration
1501 }
1502 \end{center}
1503 \end{minipage}
1504 }}}
1505 \end{pspicture}
1506
1507 \end{slide}
1508
1509 \begin{slide}
1510
1511 \headphd
1512 {\large\bf
1513  Combinations of substitutional C and Si self-interstitials
1514 }
1515
1516 \scriptsize
1517
1518 \vspace{0.3cm}
1519
1520 \begin{minipage}{6.2cm}
1521 \begin{center}
1522 {\bf\boldmath C$_{\text{sub}}$ - \si{} \hkl<1 1 0> interaction}
1523 \begin{itemize}
1524  \item Most favorable: \cs{} along \hkl<1 1 0> chain of \si{}
1525  \item Less favorable than ground-state \ci{} \hkl<1 0 0> DB
1526  \item Interaction drops quickly to zero\\
1527        $\rightarrow$ low capture radius
1528 \end{itemize}
1529 \end{center}
1530 \end{minipage}
1531 \begin{minipage}{0.2cm}
1532 \hfill
1533 \end{minipage}
1534 \begin{minipage}{6.0cm}
1535 \begin{center}
1536 {\bf Transition from the ground state}
1537 \begin{itemize}
1538  \item Low transition barrier
1539  \item Barrier smaller than \ci{} migration barrier
1540  \item Low \si{} migration barrier (\unit[0.67]{eV})\\
1541        $\rightarrow$ Separation of \cs{} \& \si{} most probable
1542 \end{itemize}
1543 \end{center}
1544 \end{minipage}\\[0.3cm]
1545
1546 \begin{minipage}{6.0cm}
1547 \includegraphics[width=6.0cm]{c_sub_si110.ps}
1548 \end{minipage}
1549 \begin{minipage}{0.4cm}
1550 \hfill
1551 \end{minipage}
1552 \begin{minipage}{6.0cm}
1553 \begin{flushright}
1554 \includegraphics[width=6.0cm]{162-097.ps}
1555 \end{flushright}
1556 \end{minipage}
1557
1558 \begin{pspicture}(0,0)(0,0)
1559 \psline[linewidth=0.05cm,linecolor=gray](6.5,0)(6.5,7.5)
1560 \rput(6.5,-0.7){\rnode{init}{\psframebox[fillstyle=solid,fillcolor=white,linewidth=0.05cm,linecolor=blue]{
1561 \begin{minipage}{8cm}
1562 \begin{center}
1563 \vspace{0.1cm}
1564 {\color{black}
1565 \cs{} \& \si{} instead of thermodynamic ground state\\[0.1cm]
1566 IBS --- process far from equilibrium\\
1567 }
1568 \end{center}
1569 \end{minipage}
1570 }}}
1571 \end{pspicture}
1572
1573 \end{slide}
1574
1575 \begin{slide}
1576
1577 \headphd
1578 {\large\bf
1579  Combinations of substitutional C and Si self-interstitials
1580 }
1581
1582 \scriptsize
1583
1584 \vspace{0.3cm}
1585
1586 \begin{minipage}{6.2cm}
1587 \begin{center}
1588 {\bf\boldmath C$_{\text{sub}}$ - \si{} \hkl<1 1 0> interaction}
1589 \begin{itemize}
1590  \item Most favorable: \cs{} along \hkl<1 1 0> chain of \si{}
1591  \item Less favorable than ground-state \ci{} \hkl<1 0 0> DB
1592  \item Interaction drops quickly to zero\\
1593        $\rightarrow$ low capture radius
1594 \end{itemize}
1595 \end{center}
1596 \end{minipage}
1597 \begin{minipage}{0.2cm}
1598 \hfill
1599 \end{minipage}
1600 \begin{minipage}{6.0cm}
1601 \begin{center}
1602 {\bf Transition from the ground state}
1603 \begin{itemize}
1604  \item Low transition barrier
1605  \item Barrier smaller than \ci{} migration barrier
1606  \item Low \si{} migration barrier (\unit[0.67]{eV})\\
1607        $\rightarrow$ Separation of \cs{} \& \si{} most probable
1608 \end{itemize}
1609 \end{center}
1610 \end{minipage}\\[0.3cm]
1611
1612 \begin{minipage}{6.0cm}
1613 \includegraphics[width=6.0cm]{c_sub_si110.ps}
1614 \end{minipage}
1615 \begin{minipage}{0.4cm}
1616 \hfill
1617 \end{minipage}
1618 \begin{minipage}{6.0cm}
1619 \begin{flushright}
1620 \includegraphics[width=6.0cm]{162-097.ps}
1621 \end{flushright}
1622 \end{minipage}
1623
1624 \begin{pspicture}(0,0)(0,0)
1625 \psline[linewidth=0.05cm,linecolor=gray](6.5,0)(6.5,7.5)
1626 \rput(6.5,-0.7){\rnode{init}{\psframebox[fillstyle=solid,fillcolor=white,linewidth=0.05cm,linecolor=blue]{
1627 \begin{minipage}{8cm}
1628 \begin{center}
1629 \vspace{0.1cm}
1630 {\color{black}
1631 \cs{} \& \si{} instead of thermodynamic ground state\\[0.1cm]
1632 IBS --- process far from equilibrium\\
1633 }
1634 \end{center}
1635 \end{minipage}
1636 }}}
1637 \end{pspicture}
1638
1639 % md support
1640 \begin{pspicture}(0,0)(0,0)
1641 \rput(6.5,5.0){\psframebox[fillstyle=solid,opacity=0.5,fillcolor=black]{
1642 \begin{minipage}{14cm}
1643 \hfill
1644 \vspace{14cm}
1645 \end{minipage}
1646 }}
1647 \rput(6.5,4.3){\rnode{init}{\psframebox[fillstyle=solid,fillcolor=white,linewidth=0.1cm]{
1648 \begin{minipage}{11cm}
1649 \begin{center}
1650 \vspace{0.2cm}
1651 \scriptsize
1652 Ab initio MD at \degc{900}\\[0.4cm]
1653 \begin{minipage}{5.4cm}
1654 \centering
1655 \includegraphics[width=4.3cm]{md01_bonds.eps}\\
1656 $t=\unit[2230]{fs}$
1657 \end{minipage}
1658 \begin{minipage}{5.4cm}
1659 \centering
1660 \includegraphics[width=4.3cm]{md02_bonds.eps}\\
1661 $t=\unit[2900]{fs}$
1662 \end{minipage}\\[0.5cm]
1663 {\color{blue}
1664 Contribution of entropy to structural formation\\[0.1cm]
1665 }
1666 \end{center}
1667 \end{minipage}
1668 }}}
1669 \end{pspicture}
1670
1671 \end{slide}
1672
1673 \begin{slide}
1674
1675 \headphd
1676 {\large\bf
1677  Silicon carbide precipitation simulations
1678 }
1679
1680 \small
1681
1682 \vspace{0.2cm}
1683
1684 {\bf Procedure}
1685
1686 {\scriptsize
1687  \begin{pspicture}(0,0)(12,6.5)
1688   % nodes
1689   \rput(3.5,5.2){\rnode{init}{\psframebox[fillstyle=solid,fillcolor=hb]{
1690    \parbox{7cm}{
1691    \begin{itemize}
1692     \item Create c-Si volume
1693     \item Periodc boundary conditions
1694     \item Set requested $T$ and $p=0\text{ bar}$
1695     \item Equilibration of $E_{\text{kin}}$ and $E_{\text{pot}}$
1696    \end{itemize}
1697   }}}}
1698   \rput(3.5,2.7){\rnode{insert}{\psframebox[fillstyle=solid,fillcolor=lachs]{
1699    \parbox{7cm}{
1700    Insertion of C atoms at constant T
1701    \begin{itemize}
1702     \item total simulation volume {\pnode{in1}}
1703     \item volume of minimal SiC precipitate size {\pnode{in2}}
1704     \item volume consisting of Si atoms to form a minimal {\pnode{in3}}\\
1705           precipitate
1706    \end{itemize} 
1707   }}}}
1708   \rput(3.5,1){\rnode{cool}{\psframebox[fillstyle=solid,fillcolor=lbb]{
1709    \parbox{7.0cm}{
1710    Run for 100 ps followed by cooling down to $20\, ^{\circ}\textrm{C}$
1711   }}}}
1712   \ncline[]{->}{init}{insert}
1713   \ncline[]{->}{insert}{cool}
1714   \psframe[fillstyle=solid,fillcolor=white](7.3,0.7)(12.8,6.3)
1715   \rput(7.6,6){\footnotesize $V_1$}
1716   \psframe[fillstyle=solid,fillcolor=lightgray](8.7,2)(11.6,5)
1717   \rput(8.9,4.85){\tiny $V_2$}
1718   \psframe[fillstyle=solid,fillcolor=gray](8.95,2.25)(11.35,4.75)
1719   \rput(9.25,4.45){\footnotesize $V_3$}
1720   \rput(7.9,3.2){\pnode{ins1}}
1721   \rput(8.92,2.8){\pnode{ins2}}
1722   \rput(10.8,2.4){\pnode{ins3}}
1723   \ncline[]{->}{in1}{ins1}
1724   \ncline[]{->}{in2}{ins2}
1725   \ncline[]{->}{in3}{ins3}
1726  \end{pspicture}
1727 }
1728
1729 \vspace{-0.5cm}
1730
1731 {\bf Note}
1732
1733 \footnotesize
1734
1735 \begin{minipage}{5.7cm}
1736 \begin{itemize}
1737  \item Amount of C atoms: 6000\\
1738        ($r_{\text{prec}}\approx 3.1\text{ nm}$, IBS: \unit[2--4]{nm})
1739  \item Simulation volume: $31^3$ Si unit cells\\
1740        (238328 Si atoms)
1741 \end{itemize}
1742 \end{minipage}
1743 \begin{minipage}{0.3cm}
1744 \hfill
1745 \end{minipage}
1746 \framebox{
1747 \begin{minipage}{6.0cm}
1748 Restricted to classical potential caclulations\\
1749 $\rightarrow$ Low C diffusion / overestimated barrier\\
1750 $\rightarrow$ Consider $V_2$ and $V_3$
1751 %\begin{itemize}
1752 % \item $V_2$ and $V_3$ considered due to expected low C diffusion
1753 %\end{itemize}
1754 \end{minipage}
1755 }
1756
1757 \end{slide}
1758
1759 \begin{slide}
1760
1761 \headphd
1762 {\large\bf\boldmath
1763  Silicon carbide precipitation simulations at \degc{450} as in IBS
1764 }
1765
1766 \small
1767
1768 \begin{minipage}{6.3cm}
1769 \hspace*{-0.4cm}\includegraphics[width=6.5cm]{sic_prec_450_si-c.ps}\\
1770 \hspace*{-0.4cm}\includegraphics[width=6.5cm]{sic_prec_450_si-si_c-c.ps}
1771 \hfill
1772 \end{minipage} 
1773 \begin{minipage}{6.1cm}
1774 \scriptsize
1775 \underline{Low C concentration --- {\color{red}$V_1$}}\\[0.1cm]
1776 \hkl<1 0 0> C-Si dumbbell dominated structure
1777 \begin{itemize}
1778  \item Si-C bumbs around \unit[0.19]{nm}
1779  \item C-C peak at \unit[0.31]{nm} (expected in 3C-SiC):\\
1780        concatenated differently oriented \ci{} DBs
1781  \item Si-Si NN distance stretched to \unit[0.3]{nm}
1782 \end{itemize}
1783 \begin{pspicture}(0,0)(6.0,1.0)
1784 \rput(3.2,0.5){\psframebox[linewidth=0.03cm,linecolor=blue]{
1785 \begin{minipage}{6cm}
1786 \centering
1787 Formation of \ci{} dumbbells\\
1788 C atoms in proper 3C-SiC distance first
1789 \end{minipage}
1790 }}
1791 \end{pspicture}\\[0.1cm]
1792 \underline{High C concentration --- {\color{green}$V_2$}/{\color{blue}$V_3$}}
1793 \begin{itemize}
1794 \item High amount of strongly bound C-C bonds
1795 \item Increased defect \& damage density\\
1796       $\rightarrow$ Arrangements hard to categorize and trace
1797 \item Only short range order observable
1798 \end{itemize}
1799 \begin{pspicture}(0,0)(6.0,0.8)
1800 \rput(3.2,0.5){\psframebox[linewidth=0.03cm,linecolor=blue]{
1801 \begin{minipage}{6cm}
1802 \centering
1803 Amorphous SiC-like phase
1804 \end{minipage}
1805 }}
1806 \end{pspicture}\\[0.3cm]
1807 \begin{pspicture}(0,0)(6.0,2.0)
1808 \rput(3.2,1.0){\psframebox[linewidth=0.05cm,linecolor=white]{
1809 \begin{minipage}{6cm}
1810 \hfill
1811 \vspace{2.5cm}
1812 \end{minipage}
1813 }}
1814 \end{pspicture}
1815 \end{minipage} 
1816
1817 \end{slide}
1818
1819 \begin{slide}
1820
1821 \headphd
1822 {\large\bf\boldmath
1823  Silicon carbide precipitation simulations at \degc{450} as in IBS
1824 }
1825
1826 \small
1827
1828 \begin{minipage}{6.3cm}
1829 \hspace*{-0.4cm}\includegraphics[width=6.5cm]{sic_prec_450_si-c.ps}\\
1830 \hspace*{-0.4cm}\includegraphics[width=6.5cm]{sic_prec_450_si-si_c-c.ps}
1831 \hfill
1832 \end{minipage} 
1833 \begin{minipage}{6.1cm}
1834 \scriptsize
1835 \underline{Low C concentration --- {\color{red}$V_1$}}\\[0.1cm]
1836 \hkl<1 0 0> C-Si dumbbell dominated structure
1837 \begin{itemize}
1838  \item Si-C bumbs around \unit[0.19]{nm}
1839  \item C-C peak at \unit[0.31]{nm} (expected in 3C-SiC):\\
1840        concatenated differently oriented \ci{} DBs
1841  \item Si-Si NN distance stretched to \unit[0.3]{nm}
1842 \end{itemize}
1843 \begin{pspicture}(0,0)(6.0,1.0)
1844 \rput(3.2,0.5){\psframebox[linewidth=0.03cm,linecolor=blue]{
1845 \begin{minipage}{6cm}
1846 \centering
1847 Formation of \ci{} dumbbells\\
1848 C atoms in proper 3C-SiC distance first
1849 \end{minipage}
1850 }}
1851 \end{pspicture}\\[0.1cm]
1852 \underline{High C concentration --- {\color{green}$V_2$}/{\color{blue}$V_3$}}
1853 \begin{itemize}
1854 \item High amount of strongly bound C-C bonds
1855 \item Increased defect \& damage density\\
1856       $\rightarrow$ Arrangements hard to categorize and trace
1857 \item Only short range order observable
1858 \end{itemize}
1859 \begin{pspicture}(0,0)(6.0,0.8)
1860 \rput(3.2,0.5){\psframebox[linewidth=0.03cm,linecolor=blue]{
1861 \begin{minipage}{6cm}
1862 \centering
1863 Amorphous SiC-like phase
1864 \end{minipage}
1865 }}
1866 \end{pspicture}\\[0.3cm]
1867 \begin{pspicture}(0,0)(6.0,2.0)
1868 \rput(3.2,1.0){\psframebox[linewidth=0.05cm,linecolor=black]{
1869 \begin{minipage}{6cm}
1870 \vspace{0.1cm}
1871 \centering
1872 {\bf\color{red}3C-SiC formation fails to appear}\\[0.3cm]
1873 \begin{minipage}{0.8cm}
1874 {\bf\boldmath $V_1$:}
1875 \end{minipage}
1876 \begin{minipage}{5.1cm}
1877 Formation of \ci{} indeed occurs\\
1878 Agllomeration not observed
1879 \end{minipage}\\[0.3cm]
1880 \begin{minipage}{0.8cm}
1881 {\bf\boldmath $V_{2,3}$:}
1882 \end{minipage}
1883 \begin{minipage}{5.1cm}
1884 Amorphous SiC-like structure\\
1885 (not expected at \degc{450})\\[0.05cm]
1886 No rearrangement/transition into 3C-SiC
1887 \end{minipage}\\[0.1cm]
1888 \end{minipage}
1889 }}
1890 \end{pspicture}
1891 \end{minipage} 
1892
1893 \end{slide}
1894
1895 \begin{slide}
1896
1897 \headphd
1898 {\large\bf
1899  Limitations of MD and short range potentials
1900 }
1901
1902 \small
1903
1904 \vspace{0.2cm}
1905
1906 {\bf Time scale problem of MD}\\[0.2cm]
1907 Precise integration \& thermodynamic sampling\\
1908 $\Rightarrow$ $\Delta t \ll \left( \max{\omega} \right)^{-1}$,
1909               $\omega$: vibrational mode\\
1910 $\Rightarrow$ {\color{red}\underline{Slow}} phase space propagation\\[0.2cm]
1911 Several local minima separated by large energy barriers\\
1912 $\Rightarrow$ Transition event corresponds to a multiple
1913               of vibrational periods\\
1914 $\Rightarrow$ Phase transition consists of {\color{red}\underline{many}}
1915               infrequent transition events\\[0.2cm]
1916 {\color{blue}Accelerated methods:}
1917 \underline{Temperature accelerated} MD (TAD), self-guided MD \ldots
1918
1919 \vspace{0.2cm}
1920
1921 {\bf Limitations related to the short range potential}\\[0.2cm]
1922 Cut-off function limits interaction to next neighbours\\
1923 $\Rightarrow$ Overestimated unphysical high forces of next neighbours
1924               (factor: 2.4--3.4)
1925
1926 \vspace{1.4cm}
1927
1928 {\bf Approach to the (twofold) problem}\\[0.2cm]
1929 Increased temperature simulations without TAD corrections\\
1930 Accelerated methods or higher time scales exclusively not sufficient!
1931
1932 \begin{pspicture}(0,0)(0,0)
1933 \rput(4.0,2.8){\psframebox[linewidth=0.07cm,linecolor=red]{
1934 \begin{minipage}{7.5cm}
1935 \centering
1936 \vspace{0.05cm}
1937 Potential enhanced slow phase space propagation
1938 \end{minipage}
1939 }}
1940 \rput(11.3,7.5){\psframebox[linewidth=0.03cm,linecolor=blue]{
1941 \begin{minipage}{2.7cm}
1942 \tiny
1943 \centering
1944 retain proper\\
1945 thermodynamic sampling
1946 \end{minipage}
1947 }}
1948 \psline[linewidth=0.03cm,linecolor=blue]{<-}(11.3,7.0)(11.0,5.7)
1949 \rput(10.85,2.6){\psframebox[linewidth=0.03cm,linecolor=blue]{
1950 \begin{minipage}{3.6cm}
1951 \tiny
1952 \centering
1953 \underline{IBS}\\[0.1cm]
1954 3C-SiC also observed for higher T\\[0.1cm]
1955 Higher T inside sample\\[0.1cm]
1956 Structural evolution vs.\\
1957 equilibrium properties
1958 \end{minipage}
1959 }}
1960 \psline[linewidth=0.03cm,linecolor=blue]{->}(10.85,1.75)(9.0,1.0)
1961 \end{pspicture}
1962
1963 \end{slide}
1964
1965 \begin{slide}
1966
1967 \headphd
1968 {\large\bf\boldmath
1969  Increased temperature simulations --- $V_1$
1970 }
1971
1972 \small
1973
1974 \begin{minipage}{6.2cm}
1975 \hspace*{-0.4cm}\includegraphics[width=6.5cm]{tot_pc_thesis.ps}
1976 \hfill
1977 \end{minipage}
1978 \begin{minipage}{6.2cm}
1979 \includegraphics[width=6.5cm]{tot_pc3_thesis.ps}
1980 \end{minipage}
1981
1982 \begin{minipage}{6.2cm}
1983 \hspace*{-0.4cm}\includegraphics[width=6.5cm]{tot_pc2_thesis.ps}
1984 \hfill
1985 \end{minipage}
1986 \begin{minipage}{6.3cm}
1987 \scriptsize
1988  \underline{Si-C bonds:}
1989  \begin{itemize}
1990   \item Vanishing cut-off artifact (above $1650\,^{\circ}\mathrm{C}$)
1991   \item Structural change: C-Si \hkl<1 0 0> $\rightarrow$ C$_{\text{sub}}$
1992  \end{itemize}
1993  \underline{Si-Si bonds:}
1994  {\color{blue}Si-C$_{\text{sub}}$-Si} along \hkl<1 1 0>
1995  ($\rightarrow$ 0.325 nm)\\[0.1cm]
1996  \underline{C-C bonds:}
1997  \begin{itemize}
1998   \item C-C next neighbour pairs reduced (mandatory)
1999   \item Peak at 0.3 nm slightly shifted
2000         \begin{itemize}
2001          \item C-Si \hkl<1 0 0> combinations (dashed arrows)\\
2002                $\rightarrow$ C-Si \hkl<1 0 0> \& C$_{\text{sub}}$
2003                combinations (|)\\
2004                $\rightarrow$ pure {\color{blue}C$_{\text{sub}}$ combinations}
2005                ($\downarrow$)
2006          \item Range [|-$\downarrow$]:
2007                {\color{blue}C$_{\text{sub}}$ \& C$_{\text{sub}}$
2008                with nearby Si$_{\text{I}}$}
2009         \end{itemize}
2010  \end{itemize}
2011 \end{minipage}
2012
2013 \end{slide}
2014
2015 \begin{slide}
2016
2017 \headphd
2018 {\large\bf\boldmath
2019  Increased temperature simulations --- $V_1$
2020 }
2021
2022 \small
2023
2024 \begin{minipage}{6.2cm}
2025 \hspace*{-0.4cm}\includegraphics[width=6.5cm]{tot_pc_thesis.ps}
2026 \hfill
2027 \end{minipage}
2028 \begin{minipage}{6.2cm}
2029 \includegraphics[width=6.5cm]{tot_pc3_thesis.ps}
2030 \end{minipage}
2031
2032 \begin{minipage}{6.2cm}
2033 \hspace*{-0.4cm}\includegraphics[width=6.5cm]{tot_pc2_thesis.ps}
2034 \hfill
2035 \end{minipage}
2036 \begin{minipage}{6.3cm}
2037 \scriptsize
2038  \underline{Si-C bonds:}
2039  \begin{itemize}
2040   \item Vanishing cut-off artifact (above $1650\,^{\circ}\mathrm{C}$)
2041   \item Structural change: C-Si \hkl<1 0 0> $\rightarrow$ C$_{\text{sub}}$
2042  \end{itemize}
2043  \underline{Si-Si bonds:}
2044  {\color{blue}Si-C$_{\text{sub}}$-Si} along \hkl<1 1 0>
2045  ($\rightarrow$ 0.325 nm)\\[0.1cm]
2046  \underline{C-C bonds:}
2047  \begin{itemize}
2048   \item C-C next neighbour pairs reduced (mandatory)
2049   \item Peak at 0.3 nm slightly shifted
2050         \begin{itemize}
2051          \item C-Si \hkl<1 0 0> combinations (dashed arrows)\\
2052                $\rightarrow$ C-Si \hkl<1 0 0> \& C$_{\text{sub}}$
2053                combinations (|)\\
2054                $\rightarrow$ pure {\color{blue}C$_{\text{sub}}$ combinations}
2055                ($\downarrow$)
2056          \item Range [|-$\downarrow$]:
2057                {\color{blue}C$_{\text{sub}}$ \& C$_{\text{sub}}$
2058                with nearby Si$_{\text{I}}$}
2059         \end{itemize}
2060  \end{itemize}
2061 \end{minipage}
2062
2063 % conclusions
2064 \begin{pspicture}(0,0)(0,0)
2065 \rput(6.5,5.0){\psframebox[fillstyle=solid,opacity=0.5,fillcolor=black]{
2066 \begin{minipage}{14cm}
2067 \hfill
2068 \vspace{14cm}
2069 \end{minipage}
2070 }}
2071 \rput(6.5,5.0){\psframebox[fillstyle=solid,fillcolor=white,linewidth=0.1cm]{
2072 \begin{minipage}{9cm}
2073 \vspace{0.2cm}
2074 \small
2075 \begin{center}
2076 {\color{gray}\bf Conclusions on SiC precipitation}\\[0.1cm]
2077 {\Huge$\lightning$} {\color{red}\ci{}} --- vs --- {\color{blue}\cs{}} {\Huge$\lightning$}\\
2078 \end{center}
2079 \begin{itemize}
2080 \item Stretched coherent SiC structures\\
2081 $\Rightarrow$ Precipitation process involves {\color{blue}\cs}
2082 \item Explains annealing behavior of high/low T C implantations
2083       \begin{itemize}
2084        \item Low T: highly mobile {\color{red}\ci}
2085        \item High T: stable configurations of {\color{blue}\cs}
2086       \end{itemize}
2087 \item Role of \si{}
2088       \begin{itemize}
2089        \item Vehicle to rearrange \cs --- [\cs{} \& \si{} $\leftrightarrow$ \ci]
2090        \item Building block for surrounding Si host \& further SiC
2091        \item Strain compensation \ldots\\
2092              \ldots Si/SiC interface\\
2093              \ldots within stretched coherent SiC structure
2094       \end{itemize}
2095 \end{itemize}
2096 \vspace{0.2cm}
2097 \centering
2098 \psframebox[linecolor=blue,linewidth=0.05cm]{
2099 \begin{minipage}{7cm}
2100 \centering
2101 Precipitation mechanism involving \cs\\
2102 High T $\leftrightarrow$ IBS conditions far from equilibrium\\
2103 \end{minipage}
2104 }
2105 \end{minipage}
2106 \vspace{0.2cm}
2107 }}
2108 \end{pspicture}
2109
2110 \end{slide}
2111
2112 % skip high T / C conc ... only here!
2113 \ifnum1=0
2114
2115 \begin{slide}
2116
2117  {\large\bf
2118   Increased temperature simulations at high C concentration
2119  }
2120
2121 \footnotesize
2122
2123 \begin{minipage}{6.5cm}
2124 \includegraphics[width=6.4cm]{12_pc_thesis.ps}
2125 \end{minipage}
2126 \begin{minipage}{6.5cm}
2127 \includegraphics[width=6.4cm]{12_pc_c_thesis.ps}
2128 \end{minipage}
2129
2130 \vspace{0.1cm}
2131
2132 \scriptsize
2133
2134 \framebox{
2135 \begin{minipage}[t]{6.0cm}
2136 0.186 nm: Si-C pairs $\uparrow$\\
2137 (as expected in 3C-SiC)\\[0.2cm]
2138 0.282 nm: Si-C-C\\[0.2cm]
2139 $\approx$0.35 nm: C-Si-Si
2140 \end{minipage}
2141 }
2142 \begin{minipage}{0.2cm}
2143 \hfill
2144 \end{minipage}
2145 \framebox{
2146 \begin{minipage}[t]{6.0cm}
2147 0.15 nm: C-C pairs $\uparrow$\\
2148 (as expected in graphite/diamond)\\[0.2cm]
2149 0.252 nm: C-C-C (2$^{\text{nd}}$ NN for diamond)\\[0.2cm]
2150 0.31 nm: shifted towards 0.317 nm $\rightarrow$ C-Si-C
2151 \end{minipage}
2152 }
2153
2154 \begin{itemize}
2155 \item Decreasing cut-off artifact
2156 \item {\color{red}Amorphous} SiC-like phase remains
2157 \item High amount of {\color{red}damage} \& alignement to c-Si host matrix lost
2158 \item Slightly sharper peaks $\Rightarrow$ indicate slight {\color{blue}acceleration of dynamics} due to temperature
2159 \end{itemize}
2160
2161 \vspace{-0.1cm}
2162
2163 \begin{center}
2164 {\color{blue}
2165 \framebox{
2166 {\color{black}
2167 High C \& small $V$ \& short $t$
2168 $\Rightarrow$
2169 }
2170 Slow restructuring due to strong C-C bonds
2171 {\color{black}
2172 $\Leftarrow$
2173 High C \& low T implants
2174 }
2175 }
2176 }
2177 \end{center}
2178
2179 \end{slide}
2180
2181 % skipped high T / C conc
2182 \fi
2183
2184 \begin{slide}
2185
2186 {\large\bf
2187  Summary / Outlook
2188 }
2189
2190 \small
2191
2192 \begin{pspicture}(0,0)(12,1.0)
2193 \psframebox[fillstyle=gradient,gradbegin=hred,gradend=white,gradlines=1000,gradmidpoint=1.0,linestyle=none]{
2194 \begin{minipage}{11cm}
2195 {\color{black}Diploma thesis}\\
2196  \underline{Monte Carlo} simulation modeling the selforganization process\\
2197  leading to periodic arrays of nanometric amorphous SiC precipitates
2198 \end{minipage}
2199 }
2200 \end{pspicture}\\[0.4cm]
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2202 \psframebox[fillstyle=gradient,gradbegin=hblue,gradend=white,gradmidpoint=1.0,gradlines=1000,linestyle=none]{
2203 \begin{minipage}{11cm}
2204 {\color{black}Doctoral studies}\\
2205  Classical potential \underline{molecular dynamics} simulations \ldots\\
2206  \underline{Density functional theory} calculations \ldots\\[0.2cm]
2207  \ldots on defect formation and SiC precipitation in Si
2208 \end{minipage}
2209 }
2210 \end{pspicture}\\[0.5cm]
2211 \begin{pspicture}(0,0)(12,3)
2212 \psframebox[fillstyle=solid,fillcolor=white,linestyle=solid]{
2213 \begin{minipage}{11cm}
2214 \vspace{0.2cm}
2215 {\color{black}\bf How to proceed \ldots}\\[0.1cm]
2216 MC $\rightarrow$ empirical potential MD $\rightarrow$ Ground-state DFT \ldots
2217 \begin{itemize}
2218  \renewcommand\labelitemi{$\ldots$}
2219  \item beyond LDA/GGA methods \& ground-state DFT
2220 \end{itemize}
2221 Investigation of structure \& structural evolution \ldots
2222 \begin{itemize}
2223  \renewcommand\labelitemi{$\ldots$}
2224  \item electronic/optical properties
2225  \item electronic correlations
2226  \item non-equilibrium systems
2227 \end{itemize}
2228 \end{minipage}
2229 }
2230 \end{pspicture}\\[0.5cm]
2231
2232 \end{slide}
2233
2234 \begin{slide}
2235
2236  {\large\bf
2237   Acknowledgements
2238  }
2239
2240  \vspace{0.1cm}
2241
2242  \small
2243
2244  Thanks to \ldots
2245
2246  \underline{Augsburg}
2247  \begin{itemize}
2248   \item Prof. B. Stritzker (accomodation at EP \RM{4})
2249   \item Ralf Utermann (EDV)
2250  \end{itemize}
2251  
2252  \underline{Helsinki}
2253  \begin{itemize}
2254   \item Prof. K. Nordlund (MD)
2255  \end{itemize}
2256  
2257  \underline{Munich}
2258  \begin{itemize}
2259   \item Bayerische Forschungsstiftung (financial support)
2260  \end{itemize}
2261  
2262  \underline{Paderborn}
2263  \begin{itemize}
2264   \item Prof. J. Lindner (SiC)
2265   \item Prof. G. Schmidt (DFT + financial support)
2266   \item Dr. E. Rauls (DFT + SiC)
2267  \end{itemize}
2268
2269  \underline{Stuttgart}
2270 \begin{center}
2271 \framebox{
2272 \bf Thank you for your attention / invitation!
2273 }
2274 \end{center}
2275
2276 \end{slide}
2277
2278 \end{document}
2279