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.

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

Explanation:

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

Explanation:

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

Explanation:

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

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

Explanation:

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

Explanation:

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

Explanation:

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%

Explanation:

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

Explanation:

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

Explanation:

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

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