# Electrons and Holes in Semiconductor MCQ’s

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

1. What is the value of the effective density of states function in the conduction band at 300k?
a) 3*1019 cm-3
b) 0.4*10-19 cm-3
c) 2.5*1019 cm-3
d) 2.5*10-19 cm-3

2. In a semiconductor which of the following carries can contribute to the current?
a) Electrons
b) Holes
c) Both
d) None

3. Which of the following expressions represents the correct distribution of the electrons in the conduction band? (gc(E)=density of quantum states, fF(E)=Fermi dirac probability
a) n(E)=gc(E)*fF(E)
b) n(E)=gc(-E)*fF(E)
c) n(E)=gc(E)*fF(-E)
d) n(E)= gc(-E)*fF(-E)

4. Which of the following expressions represent the Fermi probability function?
a) fF(E)=exp(-[E-EF]/KT)
b) fF(E)=exp(-[EF-E]/KT)
c) fF(E)=exp([E-EF]/KT)
d) fF(E)=exp(-[EF-E]/KT)

5. What is the intrinsic electrons concentration at T=300K in Silicon?
a) 1.5*1010cm-3
b) 1.5*10-10cm-3
c) 2.5*1019cm-3
d) 2.5*10-19cm-3

6. What is the difference between the practical value and theoretical value of ni?
a) Factor of 1
b) Factor of 2
c) Factor of 3
d) Factor of 4

7. Electrons from valence band rises to conduction band when the temperature is greater than 0 k. Is it True or False?
a) True
b) False

8. The intrinsic Fermi level of a semiconductor depends on which of the following things?
a) Emidgap
b) mp*
c) mn*
d) All of the mentioned

9. The thermal equilibrium concentration of the electrons in the conduction band and the holes in the valence band depends upon?
a) Effective density of states
b) Fermi energy level
c) Both A and B
d) Neither A nor B

10. In which of the following semiconductor, the concentration of the holes and electrons is equal?
a) Intrinsic
b) Extrinsic
c) Compound
d) Elemental 5 Star
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