From 2fa00b0623a6e75a295de13d4b6a1b948de3680a Mon Sep 17 00:00:00 2001 From: hackbard Date: Wed, 10 Feb 2010 18:06:08 +0100 Subject: [PATCH] fancyhdr + migration chapter finish --- posic/thesis/defects.tex | 66 +++++++++++++++++++++++++++++++++++----- posic/thesis/intro.tex | 2 +- posic/thesis/thesis.tex | 19 ++++++++++-- 3 files changed, 76 insertions(+), 11 deletions(-) diff --git a/posic/thesis/defects.tex b/posic/thesis/defects.tex index d62b327..2206dee 100644 --- a/posic/thesis/defects.tex +++ b/posic/thesis/defects.tex @@ -541,14 +541,16 @@ Results discussed in \ref{subsection:bc} indicate, that the bond-ceneterd config Thus, the \hkl<0 0 -1> to \hkl<0 0 1> migration can be thought of a two-step mechanism in which the intermediate bond-cenetered configuration constitutes a metastable configuration. Due to symmetry it is enough to consider the transition from the bond-centered to the \hkl<1 0 0> configuration or vice versa. In the second path, the carbon atom is changing its silicon partner atom as in path one. -However, the the trajectory of the carbon atom is no longer proceeding in the \hkl(1 1 0) plane. +However, the trajectory of the carbon atom is no longer proceeding in the \hkl(1 1 0) plane. The orientation of the new dumbbell configuration is transformed from \hkl<0 0 -1> to \hkl<0 -1 0>. Again one bond is broken while another one is formed. As a last migration path, the defect is only changing its orientation. -The silicon dumbbell partner remains. +Thus, it is not responsible for long-range migration. +The silicon dumbbell partner remains the same. The bond to the face-centered silicon atom at the bottom of the unit cell breaks and a new one is formed to the face-centered atom at the forefront of the unit cell. Todo: \hkl<1 1 0> to \hkl<1 0 0> and bond-centerd configuration (in progress). Todo: \hkl<1 1 0> to \hkl<0 -1 0> (rotation of the DB, in progress). +Todo: Comparison with classical potential simulations or explanation to only focus on ab initio calculations. Since the starting and final structure, which are both local minima of the potential energy surface, are known, the aim is to find the minimum energy path from one local minimum to the other one. One method to find a minimum energy path is to move the diffusing atom stepwise from the starting to the final position and only allow relaxation in the plane perpendicular to the direction of the vector connecting its starting and final position. @@ -576,6 +578,12 @@ Todo: To refine the migration barrier one has to find the saddle point structure \begin{picture}(0,0)(-120,0) \includegraphics[width=2.5cm]{vasp_mig/bc.eps} \end{picture} +\begin{picture}(0,0)(25,20) +\includegraphics[width=2.5cm]{110_arrow.eps} +\end{picture} +\begin{picture}(0,0)(200,0) +\includegraphics[height=2.2cm]{001_arrow.eps} +\end{picture} \end{center} \caption[Migration barrier and structures of the \hkl<0 0 -1> dumbbell (left) to bond-centered (right) transition.]{Migration barrier and structures of the \hkl<0 0 -1> dumbbell (left) to bond-centered (right) transition. Bonds of the carbon atoms are illustrated by blue lines.} \label{fig:defects:00-1_001_mig} @@ -583,23 +591,65 @@ Todo: To refine the migration barrier one has to find the saddle point structure In figure \ref{fig:defects:00-1_001_mig} results of the \hkl<0 0 -1> to \hkl<0 0 1> migration fully described by the migration of the \hkl<0 0 -1> dumbbell to the bond-ceneterd configuration is displayed. To reach the bond-centered configuration, which is 0.94 eV higher in energy than the \hkl<0 0 -1> dumbbell configuration, an energy barrier of approximately 1.2 eV, given by the saddle point structure at a displacement of 60 \%, has to be passed. This amount of energy is needed to break the bond of the carbon atom to the silicon atom at the bottom left. +In a second process 0.25 eV of energy are needed for the system to revert into a \hkl<1 0 0> configuration. \begin{figure}[h] \begin{center} -\includegraphics[width=13cm]{im_00-1_nosym_sp_fullct_thesis.ps}\\[0.5cm] -\begin{picture}(0,0)(150,0) -\includegraphics[width=2.5cm]{vasp_mig/00-1.eps} +\includegraphics[width=13cm]{vasp_mig/00-1_0-10_nosym_sp_fullct.ps}\\[0.5cm] +\begin{picture}(0,0)(140,0) +\includegraphics[width=2.5cm]{vasp_mig/00-1_a.eps} \end{picture} -\begin{picture}(0,0)(-10,0) -\includegraphics[width=2.5cm]{vasp_mig/bc_00-1_sp.eps} +\begin{picture}(0,0)(20,0) +\includegraphics[width=2.5cm]{vasp_mig/00-1_0-10_sp.eps} \end{picture} \begin{picture}(0,0)(-120,0) -\includegraphics[width=2.5cm]{vasp_mig/bc.eps} +\includegraphics[width=2.5cm]{vasp_mig/0-10.eps} +\end{picture} +\begin{picture}(0,0)(25,20) +\includegraphics[width=2.5cm]{100_arrow.eps} +\end{picture} +\begin{picture}(0,0)(200,0) +\includegraphics[height=2.2cm]{001_arrow.eps} \end{picture} \end{center} \caption[Migration barrier and structures of the \hkl<0 0 -1> dumbbell (left) to the \hkl<0 -1 0> dumbbell (right) transition.]{Migration barrier and structures of the \hkl<0 0 -1> dumbbell (left) to the \hkl<0 -1 0> dumbbell (right) transition. Bonds of the carbon atoms are illustrated by blue lines.} \label{fig:defects:00-1_0-10_mig} \end{figure} +Figure \ref{fig:defects:00-1_0-10_mig} shows the migration barrier and structures of the \hkl<0 0 -1> to \hkl<0 -1 0> dumbbell transition. +The resulting migration barrier of approximately 0.9 eV is very close to the experimentally obtained values of 0.73 \cite{song90} and 0.87 eV \cite{tipping87}. + +\begin{figure}[h] +\begin{center} +\includegraphics[width=13cm]{vasp_mig/00-1_ip0-10_nosym_sp_fullct.ps}\\[0.5cm] +\begin{picture}(0,0)(140,0) +\includegraphics[width=2.2cm]{vasp_mig/00-1_b.eps} +\end{picture} +\begin{picture}(0,0)(20,0) +\includegraphics[width=2.2cm]{vasp_mig/00-1_ip0-10_sp.eps} +\end{picture} +\begin{picture}(0,0)(-120,0) +\includegraphics[width=2.2cm]{vasp_mig/0-10_b.eps} +\end{picture} +\begin{picture}(0,0)(25,20) +\includegraphics[width=2.5cm]{100_arrow.eps} +\end{picture} +\begin{picture}(0,0)(200,0) +\includegraphics[height=2.2cm]{001_arrow.eps} +\end{picture} +\end{center} +\caption[Migration barrier and structures of the \hkl<0 0 -1> dumbbell (left) to the \hkl<0 -1 0> dumbbell (right) transition in place.]{Migration barrier and structures of the \hkl<0 0 -1> dumbbell (left) to the \hkl<0 -1 0> dumbbell (right) transition in place. Bonds of the carbon atoms are illustrated by blue lines.} +\label{fig:defects:00-1_0-10_ip_mig} +\end{figure} +The third migration path in which the dumbbell is changing its orientation is shown in figure \ref{fig:defects:00-1_0-10_ip_mig}. +An energy barrier of roughly 1.2 eV is observed. +Experimentally measured activation energies for reorientation range from 0.77 eV to 0.88 eV \cite{watkins76,song90}. +Thus, this pathway is more likely to be composed of two consecutive steps of the second path. + +Since the activation energy of the first and last migration path is much greater than the experimental value, the second path is identified to be responsible as a migration path for the most likely carbon interstitial in silicon explaining both, annealing and reorientation experiments. +The activation energy of roughly 0.9 eV nicely compares to experimental values. +The theoretical description performed in this work is improved compared to a former study \cite{capaz94}, which underestimates the experimental value by 35 \%. +In addition the bond-ceneterd configuration, for which spin polarized calculations are necessary, is found to be a real local minimum instead of a saddle point configuration. \section{Combination of point defects} + diff --git a/posic/thesis/intro.tex b/posic/thesis/intro.tex index 6835cd7..bb42d03 100644 --- a/posic/thesis/intro.tex +++ b/posic/thesis/intro.tex @@ -18,7 +18,7 @@ These C-Si dumbbells agglomerate and once a critical radius is reached, the topo A better understanding of the supposed SiC conversion mechanism and related carbon-mediated effects in silicon will enable significant technological progress in SiC thin film formation on the one hand and likewise offer perspectives for processes which rely upon prevention of precipitation events for improved silicon based devices on the other hand. Implanted carbon is known to suppress transient enhanced diffusion (TED) of dopant species like boron or phosphorus in the annealing step \cite{cowern96} which can be exploited to create shallow p-n junctions in submicron technologies. -Si self-interstitials (Si$_{\text{i}}$), known as the transport vehicles for dopants \cite{fahey89,stolk95}, get trapped by reacting with the carbon atoms. +Si self-interstitials (Si$_{\text{i}}$), known as the transport vehicles for dopants \cite{fahey89,stolk95}, get trapped by reacting with the carbon atoms \cite{stolk97}. Furthermore, carbon incorporated in silicon is being used to fabricate strained silicon \cite{strane94,strane96,osten99} utilized in semiconductor industry for increased charge carrier mobilities in silicon \cite{chang05,osten97} as well as to adjust its band gap \cite{soref91,kasper91}. Thus the understanding of carbon in silicon either as an isovalent impurity as well as at concentrations exceeding the solid solubility limit up to the stoichiometric ratio to form silicon carbide is of fundamental interest. diff --git a/posic/thesis/thesis.tex b/posic/thesis/thesis.tex index c2b7c43..48c2546 100644 --- a/posic/thesis/thesis.tex +++ b/posic/thesis/thesis.tex @@ -16,11 +16,12 @@ \usepackage{pstricks} \usepackage{pst-node} \usepackage{rotating} -%\usepackage{fancyhdr} -%\pagestyle{fancy} +\usepackage{fancyhdr} \usepackage{miller} +\usepackage{slashbox} + % (re)new commands \newcommand{\printimg}[5]{% \begin{figure}[#1]% @@ -37,6 +38,19 @@ % \renewcommand{\tablename}{Table}% %} +\pagestyle{fancy} +\fancyhf{} +\fancyhead[EL]{\thepage} +\fancyhead[ER]{\leftmark} +\fancyhead[OL]{\rightmark} +\fancyhead[OR]{\thepage} +\renewcommand{\sectionmark}[1]{ + \markboth{\thesection{} #1}{\thesection{} #1} +} +\renewcommand{\subsectionmark}[1]{ + \markright{\thesubsection{} #1} +} + % hyphenation \hyphenation{} @@ -67,6 +81,7 @@ \appendix{} \include{d_tersoff} +\include{vasp_patch} \include{publications} \backmatter{} -- 2.39.2