started initial part of prec models

[lectures/latex.git] / posic / thesis / sic.tex

diff --git a/posic/thesis/sic.tex b/posic/thesis/sic.tex
index c10fe17..8783989 100644 (file)
--- a/posic/thesis/sic.tex
+++ b/posic/thesis/sic.tex
@@ -345,13 +345,29 @@ While not being compatible to very-large-scale integration technology, C concent
 \label{section:assumed_prec}
 
 Although high-quality films of single-crystalline 3C-SiC can be produced by means of \ac{IBS} the precipitation mechanism in bulk Si is not yet fully understood.
 \label{section:assumed_prec}
 
 Although high-quality films of single-crystalline 3C-SiC can be produced by means of \ac{IBS} the precipitation mechanism in bulk Si is not yet fully understood.

-Indeed, closely investigating the large amount of literature reveals controversial ideas of SiC formation assumed by the respective authors, which are reviewed in more detail in the following.
+Indeed, closely investigating the large amount of literature reveals controversial ideas of SiC formation, which are reviewed in more detail in the following.
+
+\begin{figure}[ht]
+\begin{center}
+\subfigure[]{\label{fig:sic:hrem:c-si}\includegraphics[width=0.48\columnwidth]{tem_c-si-db.eps}}
+\subfigure[]{\label{fig:sic:hrem:sic}\includegraphics[width=0.48\columnwidth]{tem_3c-sic.eps}}
+\end{center}
+\caption{High resolution transmission electron microscopy (HREM) micrographs\cite{lindner99_2} of agglomerates of C-Si dimers showing dark contrasts and otherwise undisturbed Si lattice fringes (a) and equally sized Moir\'e patterns indicating 3C-SiC precipitates (b).}
+\label{fig:sic:hrem}
+\end{figure}
+
+\ac{HREM} investigations of C-implanted Si at room temperature followed by \ac{RTA} show the formation of C-Si dumbbell agglomerates, which are stable up to annealing temperatures of about \unit[700-800]{$\circ$C}, and a transformation into 3C-SiC precipitates at higher temperatures \cite{werner96,werner97}.
+The precipitates with diamateres between \unit[2]{nm} and \unit[5]{nm} are incorporated in the Si matrix without any remarkable strain fields, which is explained by the nearly equal atomic density of C-Si agglomerates and the SiC unit cell.
+Implantations at \unit[500]{$\circ$C} likewise suggest an initial formation of C-Si dumbbells on regular Si lattice sites, which agglomerate into large clusters \cite{lindner99_2}.
+The agglomerates of such dimers, which do not generate lattice strain but lead to a local increase of the lattice potential \cite{werner96}, are indicated by dark contrasts and otherwise undisturbed Si lattice fringes in \ac{HREM}, as can be seen in Fig.~\ref{fig:sic:hrem:c-si}.
+A topotactic transformation into a 3C-SiC precipitate occurs once a critical radius of \unit[2]{nm} to \unit[4]{nm} is reached.
+The precipitation is manifested by the disappearance of the dark contrasts in favor of Moir\'e patterns (Fig.~\ref{fig:sic:hrem:sic}) due to the lattice mismatch of \unit[20]{\%} of the 3C-SiC precipitate and the Si host.
+The insignificantly lower Si density of SiC of approximately \unit[3]{\%} compared to c-Si results in the emission of only a few excess Si atoms.

 
 

-\ac{HREM} studies \cite{werner96,werner97,eichhorn99,lindner99_2,koegler03} suggest the formation of C-Si dimers (dumbbells) on regular Si lattice sites, which agglomerate into large clusters indicated by dark contrasts and otherwise undisturbed Si lattice fringes in HREM, as can be seen in Fig.~\ref{fig:hrem:c-si}.

 
 

-A topotactic transformation into a 3C-SiC precipitate occurs once a critical radius of 2 nm to 4 nm is reached, which is manifested by the disappearance of the dark contrasts in favor of Moir\'e patterns (Fig.~\ref{fig:hrem:sic}) due to the lattice mismatch of \unit[20]{\%} of the 3C-SiC precipitate and c-Si.
+The formation of SiC by a preceeding agglomeration of C-Si dumbbells is supported by studies ... \cite{koegler03,eichhorn99}
+

 
 

-The insignificantly lower Si density of SiC ($\approx \unit[4]{\%}$) compared to c-Si results in the emission of only a few excess Si atoms.

 
 In contrast, investigations of strained Si$_{1-y}$C$_y$/Si heterostructures formed by MBE\cite{strane94,guedj98}, which incidentally involve the formation of SiC nanocrystallites, suggest an initial coherent precipitation by agglomeration of substitutional instead of interstitial C.
 
 
 In contrast, investigations of strained Si$_{1-y}$C$_y$/Si heterostructures formed by MBE\cite{strane94,guedj98}, which incidentally involve the formation of SiC nanocrystallites, suggest an initial coherent precipitation by agglomeration of substitutional instead of interstitial C.
 


@@ -368,18 +384,28 @@ The formation of substitutional C, however, is accompanied by Si self-interstiti
 Both processes are believed to compensate one another.
 
 
 Both processes are believed to compensate one another.
 
 

-cites:
-
-ibs, c-si agglom: werner96,werner97,eichhorn99,lindner99_2,koegler03
-ibs, c sub: nejim95
-ibs, indicated c sub: martin90 + conclusions reeson8x, eichhorn02
-hetero, coherent sic by sub c: strane94,guedj98
+%cites:

 
 

-more: taylor93, kitabatake contraction along 110, koegler03
+% continue with strane94 and werner96

 
 

+%ibs, c-si agglom: werner96,werner97,eichhorn99,lindner99_2,koegler03
+%hetero, coherent sic by sub c: strane94,guedj98
+%ibs, c sub: nejim95
+%ibs, indicated c sub: martin90 + conclusions reeson8x, eichhorn02
+%more: taylor93, kitabatake contraction along 110, koegler03
+%taylor93: sic prec only/more_easy if self interstitials are present

 
 %   -> skorupa 3.2: c sub vs sic prec  
 
 
 %   -> skorupa 3.2: c sub vs sic prec  
 

+% remember!
+% werner96/7: rt implants followed by rta < 800: C-Si db aggloms | > 800: 3C-SiC
+% taylor93: si_i reduces interfacial energy (explains metastability) of sic/si
+% eichhorn02: high imp temp more efficient than postimp treatment
+
+% todo
+% add sharp iface image!
+
+

 on surface ... md contraction along 110 ... kitabatake ... and ref in lindner ... rheed from si to sic ...
 
 in ibs ... lindner and skorupa ...
 on surface ... md contraction along 110 ... kitabatake ... and ref in lindner ... rheed from si to sic ...
 
 in ibs ... lindner and skorupa ...