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PS3/doc.tex
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PS3/doc.tex
@ -66,14 +66,14 @@
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\newcommand{\angstrom}{\textup{\AA}}
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\newcommand{\angstrom}{\textup{\AA}}
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\title{ECE 456 - Problem Set 3 (Part 1)}
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\title{ECE 456 - Problem Set 3}
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\date{2021-03-31}
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\date{2021-03-31}
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\author{David Lenfesty \\ lenfesty@ualberta.ca
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\author{David Lenfesty \\ lenfesty@ualberta.ca
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\and Phillip Kirwin \\ pkirwin@ualberta.ca}
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\and Phillip Kirwin \\ pkirwin@ualberta.ca}
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\pagestyle{fancy}
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\pagestyle{fancy}
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\fancyhead[L]{\textbf{ECE 456} - Problem Set 3 (Part 1)}
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\fancyhead[L]{\textbf{ECE 456} - Problem Set 3}
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\fancyhead[R]{David Lenfesty and Phillip Kirwin}
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\fancyhead[R]{David Lenfesty and Phillip Kirwin}
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\fancyfoot[C]{Page \thepage}
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\fancyfoot[C]{Page \thepage}
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\renewcommand{\headrulewidth}{1pt}
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\renewcommand{\headrulewidth}{1pt}
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@ -418,10 +418,12 @@ S_u = [1, s; s, 1];
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From this, we can finally obtain an expression for \( E(\vec{k}) \):
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From this, we can finally obtain an expression for \( E(\vec{k}) \):
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\begin{align}
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\begin{align}
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E(\vec{k}) = E_0 \pm t_c \sqrt{1 + 4\cos(k_x a)\cos(k_y b) 4 \cos^2(k_y b)}
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E(\vec{k}) = E_0 \pm t_c \sqrt{1 + 4\cos(k_x a)\cos(k_y b) + 4 \cos^2(k_y b)}
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\end{align}
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\end{align}
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\end{enumerate}
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\end{enumerate}
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\newpage
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\section*{Problem 4}
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\section*{Problem 4}
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\begin{enumerate}[align=left,leftmargin=*,labelsep=1em,label=\bfseries(\alph*)]
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\begin{enumerate}[align=left,leftmargin=*,labelsep=1em,label=\bfseries(\alph*)]
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@ -430,7 +432,7 @@ S_u = [1, s; s, 1];
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We can substitute (from the assignment) equation (24) into equation (23):
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We can substitute (from the assignment) equation (24) into equation (23):
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\begin{align}
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\begin{align}
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\sum _k i \hbar \frac{\delta}{\delta t} c_k(t) \phi_k(x) e^{-i [E(k) / \hbar] t} &= \sum _k c_k(t) \hat{H_0} \phi(x)e^{-i [E(k) \ \hbar] t} \\
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\sum _k i \hbar \frac{\partial}{\partial t} c_k(t) \phi_k(x) e^{-i [E(k) / \hbar] t} &= \sum _k c_k(t) \hat{H_0} \phi(x)e^{-i [E(k) / \hbar] t} \\
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&+ \sum _k c_k(t) U_s(x, t) \phi _k (x) e^ {-i [E(k) / \hbar] t}
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&+ \sum _k c_k(t) U_s(x, t) \phi _k (x) e^ {-i [E(k) / \hbar] t}
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\label{eq:phi}
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\label{eq:phi}
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\end{align}
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\end{align}
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@ -438,7 +440,7 @@ S_u = [1, s; s, 1];
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We can partially evaluate the derivative on the left hand side:
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We can partially evaluate the derivative on the left hand side:
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\begin{align*}
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\begin{align*}
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\frac{\delta}{\delta t} c_k(t) \phi _k(t)e^{-i [E(k) / \hbar]t} = \frac{\delta c_k(t)}{\delta t} \phi _k(t)e^{-i [E(k) / \hbar]t} - \frac{i}{\hbar} c_k(t)E(k)\phi _k (x) e^{-i [E(k) / \hbar]t}
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\frac{\partial}{\partial t} c_k(t) \phi_k(t)e^{-i [E(k) / \hbar]t} = \frac{\partial c_k(t)}{\partial t} \phi _k(t)e^{-i [E(k) / \hbar]t} - \frac{i}{\hbar} c_k(t)E(k)\phi _k (x) e^{-i [E(k) / \hbar]t}
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\end{align*}
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\end{align*}
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Expanding the rightmost term out into the summation, we get the expression \( \sum _k c_k(t) E(k) \phi _k(x) e^ {-i [E(k) / \hbar]t} \).
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Expanding the rightmost term out into the summation, we get the expression \( \sum _k c_k(t) E(k) \phi _k(x) e^ {-i [E(k) / \hbar]t} \).
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@ -446,7 +448,7 @@ S_u = [1, s; s, 1];
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and we get the final differential equation:
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and we get the final differential equation:
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\begin{align*}
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\begin{align*}
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\sum_k c_k(t) U_s(x, t) \phi _k (x) e^{-i [E(k) / \hbar]t} = \sum_k i \hbar \frac{\delta c_k(t)}{\delta t} \phi_k(x) e^{-i [E(k) / \hbar] t}
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\sum_k c_k(t) U_s(x, t) \phi _k (x) e^{-i [E(k) / \hbar]t} = \sum_k i \hbar \frac{\partial c_k(t)}{\partial t} \phi_k(x) e^{-i [E(k) / \hbar] t}
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\end{align*}
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\end{align*}
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\item %4b
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\item %4b
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@ -461,20 +463,20 @@ S_u = [1, s; s, 1];
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Starting with the initial equation
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Starting with the initial equation
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\begin{align*}
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\begin{align*}
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\sum _k c_k(t) I_{k_f k} e ^ {-i [ E(k) / \hbar ] t } = i \hbar \frac{\delta c_{k_f}(t)}{\delta t} e ^ {-i [ E(k_f) / \hbar ] t}
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\sum _k c_k(t) I_{k_f k} e ^ {-i [ E(k) / \hbar ] t } = i \hbar \frac{\partial c_{k_f}(t)}{\partial t} e ^ {-i [ E(k_f) / \hbar ] t}
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\end{align*}
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\end{align*}
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Since we approximated that \( c_k = 1 \), only when \( k = k_i \), and 0 otherwise, we can simplify
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Since we approximated that \( c_k = 1 \) only when \( k = k_i \) and is 0 otherwise, we can simplify
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the sum on the left hand side to a single element, and divide out the exponentials.
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the sum on the left hand side to a single element, and divide out the exponentials.
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\begin{align*}
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\begin{align*}
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I_{k_f k_i} e^{ i [- E(k_i) + E(k_f) / \hbar] t} = i \hbar \frac{\delta c_k(t)}{\delta t}
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I_{k_f k_i} e^{ i [- E(k_i) + E(k_f) / \hbar] t} = i \hbar \frac{\partial c_k(t)}{\partial t}
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\end{align*}
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\end{align*}
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Defining a new symbol \( \Lambda = [E(k_f) - E(k_i)] / \hbar \), we can simplify the equation to it's final form.
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Defining a new symbol \( \Lambda = [E(k_f) - E(k_i)] / \hbar \), we can simplify the equation to its final form.
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\begin{align}
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\begin{align}
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I_{k_f k_i} e^{i \Lambda t} = i \hbar \frac{\delta c_k(t)}{\delta t}
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I_{k_f k_i} e^{i \Lambda t} = i \hbar \frac{\partial c_k(t)}{\partial t}
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\end{align}
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\end{align}
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\item %4d
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\item %4d
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@ -491,11 +493,41 @@ S_u = [1, s; s, 1];
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\item %4e
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\item %4e
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To generate the points, we used a simple MATLAB script, found in Appendix (A).
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To generate the points, we used a simple MATLAB script:
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\begin{lstlisting}
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% Parameters to change
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N_D = 4.7e15;
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N_A = 1.6e15;
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% Logarithmic tick marks
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T = [ 5 6 7 8 9 10 20 30 40 50 60 70 80 90 100 200 300 ];
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gamma = 1.057e7 * T / sqrt(N_D - N_A);
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mu_n_first = 21.15e17 * (T.^(3/2) / (N_D + N_A));
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mu_n_last = (log(1 + gamma.^2) - (gamma.^2 ./ (1 + gamma.^2)));
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mu_n = mu_n_first ./ mu_n_last;
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for n = 1 : length(T)
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fprintf("T = %dK: %f\n", T(n), mu_n(n));
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end
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\end{lstlisting}
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Plotting on the provided graph, gives the following:
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\begin{minipage}[t]{\linewidth}
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\centering
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\adjustbox{valign=t}{
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\includegraphics[width=0.5\textwidth]{q4_plot.png}
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}
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\captionof{figure}{Graph of electron mobility in GaAs.}
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\end{minipage}
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It's clear that our calculated results match up well with the theoretical results.
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\end{enumerate}
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\end{enumerate}
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\app
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\end{document}
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\end{document}
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