Matlab report

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EEGR 215 Materials & Devices Lab # 2 Due March 15, 2017 Instructor: Dr. Michel Reece With the help of a computer and a commercial software package such as Matlab solve the following problems: 1. Write a Matlab program to confirm that the ni versus T curve for Ge and Si graphed in Figure 2.20 can be generated by employing the empirical fit relationships below. Check over the temperature range of 275K ≤ T ≤ 500K.  2   T  0.5928kT ni( Si)  9.15  10   e  300   19  ni(Ge)  1.76  1016 T  2 e 3 0.392 kT eqn. 1 eqn. 2 2. Generate a MATLAB program to compute and plot the Fermi function, f(E), versus ΔE = E-Ef for values of ΔE that is over the range of -0.2eV ≤ ΔE ≤ 0.2eV for varying temperature settings where Temperature = 100, 200, 300, 400 and 500K. Make sure that each f(E) versus ΔE curve at each temperature is superimposed on the same plot. Discuss what you see in your plots as the Fermi function varies with temperature and energy. 3. Consider a sample of silicon doped at Nd = 0 and Na = 1014cm-3. (a) Plot the majority carrier concentration versus temperature over the range 200 ≤ T ≤ 500K. (b) Plot the minority carrier concentration versus temperature over the range of 200 ≤ T ≤ 500K. (c) Describe what occurs to the majority carrier concentration as the temperature increases. (d) Describe what occurs to the minority carrier concentration as the temperature increases. (e) Compare your values of (c) and (d) with the intrinsic carrier concentration as a function of temperature in Problem #1 using equation 1. 4. The temperature of a sample of GaAs is T = 300K and the donor doping concentration is Nd = 0. (a) Plot the minority carrier concentration (on a log-log plot) versus Na over the range 1015 ≤ Na ≤ 1018 cm-3 . (b) Describe what happens to the minority carrier concentration as the doping concentration increases. 5. Consider GaAs over the temperature range of 300 ≤ T ≤ 500K with Na = 0. (a) Plot the position of the Fermi energy level with respect to the intrinsic Fermi energy level as a function of the donor impurity concentration of over the range of 1014 ≤ Nd ≤ 1018 cm-3 .(b) Plot the position of the Fermi energy level with respect to the valence-band energy over the same acceptor impurity concentration as given in part (a). (c) Repeat (a) and (b) for Ge. (d) Determine which semiconductor is most likely to become intrinsic at a lower temperature. Explain your answer. 6. Assuming a non-degenerate Ge sample and total impurity atom ionization, construct a MATLAB program that computes n, p, and EF – EI given acceptable input values of T (temperature in Kelvin), ND (cm-3), and NA (cm-3). Use the program to obtain check your solutions to Assignment #3, Problem #5 (a-h). (Note: Make sure to include a commented program along with the screen outputs showing solutions.)
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Explanation & Answer

Attached.

Question 1
MatLab Code
clear all;
T =275:1:500;
k = 1.38*10^(-23);
z = 1.609*10^(-19);
ni_si = (9.15*10^(19)).*((T./300).^2).*exp(-0.5928*z./(k.*T));
ni_Ge = (1.76*10^16).*(T.^(3/2)).*exp(-0.392*z./(k.*T));

plot(T,ni_si,'b');
xlabel('Temperature T')
ylabel('Intrinsic concentration')
legend('Silicon')
figure;
plot(T,ni_Ge,'r');
xlabel('Temperature T');
ylabel('Intrinsic Concentration')
legend('Germenium')

Results

Discussion
The curves above have been generated by employing the empirical fit relationships in the
equations given. This confirms that the ni versus T curve for both Germanium and silicon can be
generated using the gi...


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