Electronics I, ECE 2204, CRN 11883 Exam 1 Chapter 1&2 . Diodes
Use proper UNITS and ONLY 3 significant figures in all calculations.
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Part 1: Please circle the right answers to each question: (5% for each question)
1. For the semiconductor materials, which statements below are right?
(a) Extrinsic semiconductors can still conduct the current at T=0K, but intrinsic semiconductors
can not.
(b) For intrinsic semiconductors, the concentrations of electron and hole are always the same
(c) For N-type extrinsic semiconductors, there is only free electron as the carrier
(d) In most of the cases, majority carrier concentration can be assumed to be the same as the
impurity concentration being doped.
(e) The majority carrier of N-type semiconductor is hole, whereas the majority carrier of P-type
semiconductor materials is electron
2. For P-N junction, which statements below are right?
(a) The built-in potential barrier Vbi will be higher under higher temperature
(b) To turn-on the P-N junction, the external voltage should be higher than Vbi
(c) The width of the depletion region of the P-N junction will increase when it is reverse biased.
(d) When there is no biasing voltage across the P-N junction, there is no space-charge region
3. To converter electrical signal into optical signal (light), which diode should be used:
(a) Solar cell (b) Photodiode (c) Schottky diode (d) Light-Emitting Diode (LED)
4. Regarding the AC equivalent circuit of diode, its small-signal incremental resistance rd is:
(a) equal to forward diode resistance rf (b)
DQ
T
d
I
V
r
5. For a diode with 0.7V cut-in voltage and zero rf, and a Zener diode with 5.6V breakdown voltage
and zero rz, which circuits below can work properly?
10V
D
(a)
D
(b)
10V
D
(c)
10V
Z
(d)
10V
Z
(e)
10V
Z
(f)
10V
