From: hackbard Date: Wed, 28 Sep 2011 08:40:49 +0000 (+0200) Subject: final stuff X-Git-Url: https://hackdaworld.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=0f2f4d7219f15894677fa9247f65a2ae229fddfb;p=lectures%2Flatex.git final stuff --- diff --git a/posic/thesis/defects.tex b/posic/thesis/defects.tex index eab8a4e..5e2c83e 100644 --- a/posic/thesis/defects.tex +++ b/posic/thesis/defects.tex @@ -1301,29 +1301,29 @@ Strain reduced by this huge displacement is partially absorbed by tensile strain A binding energy of \unit[-0.50]{eV} is observed. The migration pathways of configuration~\ref{fig:defects:314} and~\ref{fig:defects:059} into the ground-state configuration, i.e.\ the \cs{} configuration, are shown in Fig.~\ref{fig:314-539} and~\ref{fig:059-539} respectively. -\begin{figure}[tp] -\begin{center} -\includegraphics[width=0.7\textwidth]{314-539.ps} -\end{center} -\caption[Migration barrier and structures of the transition of the initial C$_{\text{i}}$ {\hkl[0 0 -1]} DB and a V created at position 3 into a C$_{\text{s}}$ configuration.]{Migration barrier and structures of the transition of the initial C$_{\text{i}}$ \hkl[0 0 -1] DB and a V created at position 3 (left) into a C$_{\text{s}}$ configuration (right). An activation energy of \unit[0.1]{eV} is observed.} -\label{fig:314-539} -\end{figure} -\begin{figure}[tp] -\begin{center} -\includegraphics[width=0.7\textwidth]{059-539.ps} -\end{center} -\caption[Migration barrier and structures of the transition of the initial C$_{\text{i}}$ {\hkl[0 0 -1]} DB and a V created at position 2 into a C$_{\text{s}}$ configuration.]{Migration barrier and structures of the transition of the initial C$_{\text{i}}$ \hkl[0 0 -1] DB and a V created at position 2 (left) into a C$_{\text{s}}$ configuration (right). An activation energy of \unit[0.6]{eV} is observed.} -\label{fig:059-539} -\end{figure} +\begin{figure}[tp]% +\begin{center}% +\includegraphics[width=0.7\textwidth]{314-539.ps}% +\end{center}% +\caption[Migration barrier and structures of the transition of the initial C$_{\text{i}}$ {\hkl[0 0 -1]} DB and a V created at position 3 into a C$_{\text{s}}$ configuration.]{Migration barrier and structures of the transition of the initial C$_{\text{i}}$ \hkl[0 0 -1] DB and a V created at position 3 (left) into a C$_{\text{s}}$ configuration (right). An activation energy of \unit[0.1]{eV} is observed.}% +\label{fig:314-539}% +\end{figure}% +\begin{figure}[tp]% +\begin{center}% +\includegraphics[width=0.7\textwidth]{059-539.ps}% +\end{center}% +\caption[Migration barrier and structures of the transition of the initial C$_{\text{i}}$ {\hkl[0 0 -1]} DB and a V created at position 2 into a C$_{\text{s}}$ configuration.]{Migration barrier and structures of the transition of the initial C$_{\text{i}}$ \hkl[0 0 -1] DB and a V created at position 2 (left) into a C$_{\text{s}}$ configuration (right). An activation energy of \unit[0.6]{eV} is observed.}% +\label{fig:059-539}% +\end{figure}% Activation energies as low as \unit[0.1]{eV} and \unit[0.6]{eV} are observed. In the first case, the Si and C atom of the DB move towards the vacant and initial DB lattice site respectively. -In total three Si-Si and one more Si-C bond is formed during transition. +In total, three Si-Si and one more Si-C bond is formed during transition. The activation energy of \unit[0.1]{eV} is needed to tilt the DB structure. Once this barrier is overcome, the C atom forms a bond to the top left Si atom and the \si{} atom capturing the vacant site is forming new tetrahedral bonds to its neighbored Si atoms. These new bonds and the relaxation into the \cs{} configuration are responsible for the gain in configurational energy. For the reverse process approximately \unit[2.4]{eV} are needed, which is 24 times higher than the forward process. In the second case, the lowest barrier is found for the migration of Si number 1, which is substituted by the C$_{\text{i}}$ atom, towards the vacant site. -A net amount of five Si-Si and one Si-C bond are additionally formed during transition. +A net amount of five Si-Si bonds and one Si-C bond are additionally formed during transition. An activation energy of \unit[0.6]{eV} necessary to overcome the migration barrier is found. This energy is low enough to constitute a feasible mechanism in SiC precipitation. To reverse this process, \unit[5.4]{eV} are needed, which make this mechanism very improbable. @@ -1350,7 +1350,7 @@ So far, the C-Si \hkl<1 0 0> DB interstitial was found to be the energetically m In fact, substitutional C exhibits a configuration more than \unit[3]{eV} lower with respect to the formation energy. However, the configuration does not account for the accompanying Si self-interstitial that is generated once a C atom occupies the site of a Si atom. With regard to the IBS process, in which highly energetic C atoms enter the Si target being able to kick out Si atoms from their lattice sites, such configurations are absolutely conceivable and a significant influence on the precipitation process might be attributed to them. -Thus, combinations of \cs{} and an additional \si{} are examined in the following. +Thus, combinations of \cs{} with an additional \si{} are examined in the following. The ground-state of a single \si{} was found to be the \si{} \hkl<1 1 0> DB configuration. For the following study, the same type of self-interstitial is assumed to provide the energetically most favorable configuration in combination with \cs.