Problem 1
(a) How is the depletion width of a pn-junction related to the doping?
(b) How can the depletion width be measured experimentally?
(c) What is the built-in voltage $V_{bi}$ of a pn-junction? How can you measure $V_{bi}$?
(d) Describe a Zener diode.
Problem 2
Describe the role of recombination in a:
(a) light emitting diode
(b) bipolar transistor
(c) metal-semiconductor contact
(d) thyristor
Problem 3
(a) Draw an $n$-channel MOSFET showing the source, drain, gate, and body contacts.
(b) Draw the charge distribution, electric field, and band diagram (conduction band, valence band, Fermi energy) in inversion along a line from the gate into the body (like for a MOS capacitor).
(c) Where are the following current mechanisms dominant in a MOSFET?
Problem 4
Make a drawing of a laser diode and describe how it works. What determines the frequency that is emitted? Why is there a threshold current? How is it different from an ordinary light emitting diode?
Quantity | Symbol | Value | Units | |
| electron charge | e | 1.60217733 × 10-19 | C | |
| speed of light | c | 2.99792458 × 108 | m/s | |
| Planck's constant | h | 6.6260755 × 10-34 | J s | |
| reduced Planck's constant | $\hbar$ | 1.05457266 × 10-34 | J s | |
| Boltzmann's constant | kB | 1.380658 × 10-23 | J/K | |
| electron mass | me | 9.1093897 × 10-31 | kg | |
| Stefan-Boltzmann constant | σ | 5.67051 × 10-8 | W m-2 K-4 | |
| Bohr radius | a0 | 0.529177249 × 10-10 | m | |
| atomic mass constant | mu | 1.6605402 × 10-27 | kg | |
| permeability of vacuum | μ0 | 4π × 10-7 | N A-2 | |
| permittivity of vacuum | ε0 | 8.854187817 × 10-12 | F m-1 | |
| Avogado's constant | NA | 6.0221367 × 1023 | mol-1 |