Electronic Devices and Circuits Questions and Answers – Semiconductor Physics

This set of Electronic Devices and Circuits Multiple Choice Questions & Answers (MCQs) focuses on “Semiconductor Physics”.

In the problems assume the parameter given in the following table. Use the temperature T= 300 K unless otherwise stated.
parameters for problems and temperature T = 300 Ks
1. In germanium semiconductor material at T 400 K the intrinsic concentration is (x 10^14 per cc)
a) 26.8
b) 18.4
c) 8.5
d) 3.6
View Answer

Answer: c
Explanation: In germanium semiconductor material at T 400 K the intrinsic concentration is 8.5

2. The intrinsic carrier concentration in silicon is to be no greater than ni = 1 x 10^12 cc. The maximum temperature allowed for the silicon is ( Eg = 1.12 eV)
a) 300 K
b) 360 K
c) 382 K
d) 364 K
View Answer

Answer: c
Explanation: In germanium semiconductor material at T 400 K the intrinsic concentration is 8.5

3. Two semiconductor material have exactly the same properties except that material A has a bandgap of 1.0
eV and material B has a bandgap energy of 1.2 eV. The ratio of intrinsic concentration of material A to that of
material B is
a) 2016
b) 47.5
c) 58.23
d) 1048
View Answer

Answer: b
Explanation: The ratio of intrinsic concentration of material A to that of material B is 47.5
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4. In silicon at T = 300 K the thermal-equilibrium concentration of electron is n0 = 5 x 10^4 cc. The hole concentration is
a) 4.5 x 1015 cc
b) 4.5 x 1015 m3
c) 0.3 x 10-6 cc
d) 0.3 x 10-6 m3
View Answer

Answer: a
Explanation: ni x ni = no x po.

5. In silicon at T = 300 K if the Fermi energy is 0.22 eV above the valence band energy, the value of p0 is
a) 2 x 1015 cm3
b) 1015 cm3
c) 3 x 1015 cm3
d) 4 x 1015 cm3
View Answer

Answer: a
Explanation: The value of p0 is 2 x 1015 cm3 in silicon at T = 300 K if Fermi energy is 0.22 eV

6. The thermal-equilibrium concentration of hole p0 in silicon at T = 300 K is 1015 cm3. The value of n0 is
a) 3.8 x 108 cm3
b) 4.4 x 104 cm3
c) 2.6 x 104 cm3
d) 4.3 x 108 cm3
View Answer

Answer: b
Explanation:Value of n0 is 4.4 x 104 cm3 if thermal-equilibrium concentration at T = 300 K is 1015 cm3

7. In germanium semiconductor at T 300 K, the acceptor concentrations is Na 1013 cm3 and donor concentration is Nd 0. The thermal equilibrium concentration p0 is
a) 2.97 x 109 cm3
b) 2.68 x 1012 cm3
c) 2.95 x 1013 cm3
d) 2.4 cm3
View Answer

Answer: c
Explanation: The thermal concentration p0 is 2.95 x 1013 cm3 if semiconductor at T 300 K is Na 1013 cm3
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8. A silicon sample doped n type at 10^18 cm3 have a resistance of 10 ohm. The sample has an area of 10^(-6) cm2 and a length of 10 µm . The doping efficiency of the sample is (µn = 800 cm2/V-s )
a) 43.2%
b) 78.1%
c) 96.3%
d) 54.3%
View Answer

Answer: b
Explanation: The doping efficiency is 78.1% if silicon doped n type at 10 18 cm3 resistance of 10 ohm

9. Six volts is applied across a 2 cm long semiconductor bar. The average drift velocity is 104 cms. The electron mobility is
a) 4396 cm2/V-s 2
b) 3 x 104 cm2/V-s
c) 6 x 104 cm2V-s
d) 3333 cm2/V-s
View Answer

Answer: d
Explanation: The electron mobility is 3333 cm2/V-s for average drift velocity is 104 cms
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10. A particular intrinsic semiconductor has a resistivity of 50 (ohm-cm) at T = 300 K and 5 (ohm-cm) at T = 330 K. If change in mobility with temperature is neglected, the bandgap energy of the semiconductor is
a) 1.9 eV
b) 1.3 eV
c) 2.6 eV
d) 0.64 eV
View Answer

Answer: b
Explanation: The bandgap energy of semiconductor is 1.3 eV if change with temperature is neglected

Sanfoundry Global Education & Learning Series – Electronic Devices and Circuits.

To practice all areas of Electronic Devices and Circuits, here is complete set of 1000+ Multiple Choice Questions and Answers.

If you find a mistake in question / option / answer, kindly take a screenshot and email to [email protected]

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Manish Bhojasia - Founder & CTO at Sanfoundry
Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He lives in Bangalore, and focuses on development of Linux Kernel, SAN Technologies, Advanced C, Data Structures & Alogrithms. Stay connected with him at LinkedIn.

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