From 68e3cad24c507b63e4366c63a959e4095c0a53f3 Mon Sep 17 00:00:00 2001 From: hackbard Date: Tue, 3 May 2011 15:47:51 +0200 Subject: [PATCH] nearly finished sic chapter --- posic/thesis/sic.tex | 18 ++++++++---------- 1 file changed, 8 insertions(+), 10 deletions(-) diff --git a/posic/thesis/sic.tex b/posic/thesis/sic.tex index 78a8fdb..2acb2c4 100644 --- a/posic/thesis/sic.tex +++ b/posic/thesis/sic.tex @@ -278,7 +278,7 @@ Fig. \ref{fig:sic:hrem_sharp} shows the respective \ac{HREM} micrographs. \begin{center} \includegraphics[width=0.6\columnwidth]{ibs_3c-sic.eps} \end{center} -\caption{Bright field (a) and \hkl(1 1 1) SiC dark field (b) cross-sectional TEM micrographs of the buried SiC layer in Si created by the two-temperature implantation technique and subsequent annealing as explained in the text \cite{lindner99_2}. The inset shows a selected area diffraction pattern of the buried layer.} +\caption[Bright field (a) and \hkl(1 1 1) SiC dark field (b) cross-sectional TEM micrographs of the buried SiC layer in Si created by the two-temperature implantation technique and subsequent annealing.]{Bright field (a) and \hkl(1 1 1) SiC dark field (b) cross-sectional TEM micrographs of the buried SiC layer in Si created by the two-temperature implantation technique and subsequent annealing as explained in the text \cite{lindner99_2}. The inset shows a selected area diffraction pattern of the buried layer.} \label{fig:sic:hrem_sharp} \end{figure} @@ -298,9 +298,9 @@ Below the solid solubility, C impurities mainly occupy substitutionally Si latti Due to the much smaller covalent radius of C compared to Si every incorporated C atom leads to a decrease in the lattice constant corresponding to a lattice contraction of about one atomic volume \cite{baker68}. The induced strain is assumed to be responsible for the low solid solubility of C in Si, which was determined \cite{bean71} to be \begin{equation} -c_{\text{s}}=\unit[4\times10^{24}]{cm^{-3}} -\cdot\exp(\unit[-2.3]{eV/k_{\text{B}}T}) -\text{ .} \text{{\color{red}k recursive!}} +c_{\text{s}}=4\times10^{24}\,\text{cm$^{-3}$} +\cdot\exp(-2.3\,\text{eV/$k_{\text{B}}T$}) +\text{ .} \end{equation} The barrier of diffusion of substitutional C has been determined to be around \unit[3]{eV} \cite{newman61}. @@ -353,7 +353,7 @@ 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. -Indeed, closely investigating the large amount of literature reveals controversial ideas of SiC formation, which are reviewed in more detail in the following. +Indeed, closely investigating the large amount of literature pulled up in the last two sections and a cautios combination of some of the findings reveals controversial ideas of SiC formation, which are reviewed in more detail in the following. \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. @@ -364,7 +364,7 @@ The agglomerates of such dimers, which do not generate lattice strain but lead t \subfigure[]{\label{fig:sic:hrem:c-si}\includegraphics[width=0.25\columnwidth]{tem_c-si-db.eps}} \subfigure[]{\label{fig:sic:hrem:sic}\includegraphics[width=0.25\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).} +\caption[High resolution transmission electron microscopy (HREM) micrographs 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).]{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} A topotactic transformation into a 3C-SiC precipitate occurs once a critical radius of \unit[2]{nm} to \unit[4]{nm} is reached. @@ -411,15 +411,13 @@ To conclude, a controversy with respect to the precipitation of SiC in Si exists Next to the pure scientific interest, solving this controversy and gaining new insight in the SiC conversion mechanism might enable significant progress in the heteroepitaxial growth of thin films featuring non-coherent interfaces in the C/Si system. On the other hand, processes relying upon prevention of precipitation in order to produce strained heterostructures will likewise benefit. -% remember! - +% 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 % eichhorn99: same as 02 + c-si agglomerates at low concentrations - % strane94/guedj98: my model - c redist by si int (spe) and surface diff (mbe) % todo -% add sharp iface image! +% own polytype stacking sequence image -- 2.20.1