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+\usepackage{amsmath}
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+
+\begin{document}
+
+% header
+\begin{center}
+ {\LARGE {\bf Materials Physics I}\\}
+ \vspace{8pt}
+ Prof. B. Stritzker\\
+ WS 2007/08\\
+ \vspace{8pt}
+ {\Large\bf Tutorial 6}
+\end{center}
+
+\section{Indirect band gap of silicon}
+
+Some facts about silicon:
+\begin{itemize}
+ \item Lattice constant: $a=5.43 \cdot 10^{-10} \, m$.
+ \item Silicon has an indirect band gap.
+ \begin{itemize}
+ \item The minimum of the conduction band is located at
+ $k=0.85 \frac{2 \pi}{a}$.
+ \item The maximum of the valance band is located at $k=0$.
+ \item The energy gap is $E_g=1.12 \, eV$.
+ \end{itemize}
+\end{itemize}
+\begin{enumerate}
+ \item Calculate the wavelength of the light necessary to lift an electron from
+ the valence to the conduction band.
+ What is the momentum of such a photon?
+ \item Calculate the phonon momentum necessary for the transition.
+ Compare the momentum values of phonon and photon.
+ \item Draw conclusions concerning optical applications.
+\end{enumerate}
+
+\section{\ldots}
+
+\ldots
+
+\begin{enumerate}
+ \item \ldots
+ \item \ldots
+\end{enumerate}
+
+\end{document}