- What is a flatband diagram?
- Discuss the motion of electrons and holes in a p-n junction in thermal equilibrium.
- Define the built-in potential. Also provide an equation and state the implicit assumption(s).
- How does the energy band diagram of a p-n junction change under forward and reverse bias?
- What is the full depletion approximation? Why do we need the full depletion approximation?
- Derive equation (4.3.17) from (4.3.13), (4.3.14) and (4.3.16).
- Explain why the capacitance of a p-n junction (4.3.22) equals that of a parallel plate capacitor. How does the capacitance differ from a parallel plate capacitor?
- How do you extract the doping profile shown in Fig. 4.3.4 from the capacitance shown in Fig. 4.3.3?
- What mechanism(s) cause(s) current in a p-n junction?
- How does one calculate the current in a p-n junction?
- How does one solve the diffusion equation in the quasi-neutral regions?
- What is the difference between the "long" and "short" diode analysis?
- When can the recombination/generation current in the depletion region be ignored?
- Which saturation current is voltage dependent, that for the "long" diode or the one for the "short" diode?
- Why does one need to include edge effects when calculating the breakdown voltage of a diode?
- Name two breakdown mechanisms and discuss the temperature dependence of the resulting breakdown voltage.
- Describe the avalanche breakdown mechanism.
- Describe tunneling.
- Illustrate the generation of a photocurrent in a p-n diode by drawing an energy band diagram. Indicate the photo-generated carriers and their direction of motion.
- Why is the photocurrent negative compared to the forward bias current through the same diode?
- What limits the quantum efficiency of a photodiode?
- What is the difference between a solar cell and a photodiode?
- Why would solar cells be more efficient if the sun where a laser rather than a black body radiator?
- What limits the power conversion efficiency of a solar cell?
- Using equation 4.6.1 show that the open-circuit voltage increases as the photocurrent increases. Use this result to prove that the power conversion efficiency of a solar increases when using a concentrator which increases the incident power density.
- Why is silicon not used to fabricated LEDs or laser diodes?
- Why are planar LEDs so inefficient? How can the efficiency of an LED be improved beyond that of a planar LED?
- How does the light emitted by an LED differ from that emitted by a laser diode?
- What is stimulated emission?
- Why does a laser diode need a waveguide?
- Explain the lasing condition in words.
- Describe the power versus current characteristic of a laser diode.
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