Technologies
Electronics and Communication questions and answers for Examination
1. Resistivity measurements are often used to determine.
a. carrier mobility
b. carrier concentration in intrinsic semiconductor
c. carrier concentration in extrinsic semiconductor
d. lifetime of polycrystalline materials
2. When an electric field is applied to an intrinsic semiconductor at room temperature say from left to right.
a. both electrons and holes drift to the right
b. both electrons and holes drift to the left
c. electrons drift to the right while the holes drift to the left
d. electrons drift to the left while hole drift to the right
3. The energy required to break a covalent bond in a semiconductor is.
a. always equal to 1.6 eV
b. greater in G and S
c. equal to the width of the forbidden energy gap
d. in same in G as in S.
4. In a semiconductor rate of diffusion of charge carriers.
a. depends on the concentration gradient and the mobility
b. depends on the concentration gradient alone
c. depends on the mobility alone
d. is independent of the concentration gradient and the mobility
5. Pure semiconductor are poor conductor because
a. they have no valence electrons
b. all valence electrons are in electron pairs
c. they have a number of holes
d. there are fewer electrons than produces
6. Forbidden energy gap in the semiconductor is of the order of.
a. 7eV
b. 1eV
c. 0.1eV
d. 0.05eV
7. At 300 K , the forbidden energy gap in germanium.
a. 0.785eV
b. 1.21eV
c. 0.72eV
d. 1.1eV
8. A 0 K, the forbidden energy gap in silicon is.
a. 0.785eV
b. 1.21eV
c. 0.72eV
d. 1.1eV
9. The mobility of holes in germanium of 300 K expressed in cm^2/V-s is.
a. 500
b. 1300
c. 1800
d. 3800
10. The mobility of holes in silicon of 300 K expressed in cm^2/V-s is.
a. 500
b. 1300
c. 1800
d. 3800
Answers:
1. c
2. d
3. c
4. a
5. b
6. b
7. c
8. b
9. c
10. a
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