MCQ on Semiconductor Material

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MCQ on Semiconductor Material

MCQ on Semiconductor Material, Multiple Choice Questions on Semiconductor Material, Engineering Physics MCQ, Engineering MCQ,

Multiple Choice Questions

Q.1. Which of the following, has the lowest temperature coefficient of resistivity.

Alum Silver, Copper, Gold, Aluminium

  • Copper 
  • Silver
  • Gold
  • Aluminium 

Answer: Gold

Q.2. In a metal

  • The electrical conduction is by electrons and holes
  • With rise in temperature, the conductivity decreases
  • The conduction band is empty
  • There is a small energy gap between the two bands

Answer: With a rise in temperature, the conductivity decreases

Q.3. The forbidden energy gap in semiconductors:

  • lies just below the valence band
  • is the same as the valence band
  • lies just above the conduction band
  • lies between the valence band and the conduction band

Answer: lies between the valence band and the conduction band

Q.4. The conduction band of a semiconductor material may be

  • completely filled
  • partially filled
  • empty
  • none

Answer: partially filled

Q.5. The energy band which possesses the free electrons is called:

  • valence band
  • conduction band
  • forbidden band
  • none of these

Answer: conduction band

Q.6. Which of the following behaves as an insulator.

  • Diamond
  • Germanium
  • Silicon
  • Silver

Answer: Diamond

Q.7. The unit of mobility of charge carriers is

  • m2/volt-sec
  • m/volt-sec2
  • m3/volt-sec
  • m/volt-sec

Answer: m2/volt-sec

Q.8. A semiconductor is electrically neutral because it has:

  • no majority carriers
  • no minority carriers
  • no free carriers
  • equal number of positive and negative carriers

Answer: an equal number of positive and negative carriers

Q.9. An intrinsic semiconductor at absolute zero temperature

  • has large number of holes
  • has a few hole and same number of electrons
  • acts as an insulator
  • acts as metallic character

Answer: acts as an insulator

Q.10. When the temperature of an intrinsic semiconductor is increased

  • resistance of semiconductor is also increased
  • conductivity is decreased
  • energy of atoms is increased
  • holes are created

Answer: energy of atoms is increased

Q.11. A doner-type impurity

  • is used to obtain a p-type semiconductor
  • is used to obtain a N-type semiconductor
  • must possess three valence electrons
  • cannot be used in silicon crystals

Answer: is used to obtain an N-type semiconductor

Q.12. If a small amount of antimony is added to Ge

  • the resistance is increased
  • Ge will become a p-type semi-conductor
  • antimony becomes an acceptor impurity
  • there will be no more free electrons than holes in a semiconductor

Answer: there will be no more free electrons than holes in a semiconductor

Q.13. In an N-type semiconductor, the concentration of minority carriers mainly depends upon

  • doping technique
  • number of donor atoms
  • temperature of material
  • quality of intrinsic materials Ge or Si

Answer: temperature of material

Q.14. In a P-type semiconductor, majority carriers are

  • holes
  • electrons
  • both
  • none of the above

Answer: holes

Q.15. Which of the following atoms can be used as a p-type impurity

  • Boron
  • Arsenic
  • Antimony
  • Phosphorus  

Answer: Boron

Q.16. In an intrinsic semiconductors, the Fermi level lies:

  • in the middle of conduction band (CB) and valence band (VB)
  • near CB
  • near VB
  • none of these

Answer: in the middle of CB and VB

Q.17. 10-9 ohm-m is the resistivity of

  • Aluminium
  • Sodium
  • Bismuth
  • Nickel

Answer: Nickel

Q.18. Due to the illumination of light, the electron and hole concentrations in a heavily doped n-type semiconductor, increase by Δn and Δp respectively. If ni is the intrinsic concentration, then

  • \Delta n < \Delta p
  • \Delta n > \Delta p
  • \Delta n = \Delta p
  • \Delta n \times \Delta p = n_{i}^{2}

Answer: \Delta n \times \Delta p = n_{i}^{2}

Q.19. The current density Jo of electrons through any conductor carrying current is given by:

  • J_{0}=\frac{ne\tau E}{m}
  • J_{0}=\frac{ne\tau E^{2}}{m}
  • J_{0}=\frac{ne^{2}\tau E}{m}
  • J_{0}=\frac{e^{2}\tau E}{m}

Answer: J_{0}=\frac{ne^{2}\tau E}{m}

Q.20. An element used in semiconductors whose atoms have three valence electrons is

  • Germanium
  • A donor
  • An acceptor
  • Silicon

Answer: An acceptor

Q.21. The Hall coefficient RH is defined by

  • R_{H}=\frac{V_{H}.t}{B}
  • R_{H}=\frac{V_{H}B}{It}
  • R_{H}=\frac{V_{H}t}{B}
  • R_{H}=\frac{V_{H}t}{BI}

Answer: R_{H}=\frac{V_{H}t}{BI}

Q.22. The probability of occupation F(E) of an energy level E by an electron is given by

  • F(E)=[1+e^{(E-E_{F})}/kT]
  • F(E)=\frac{1}{1+e^{(E_{F}-E)}/kT}
  • F(E)=\frac{1}{1+e^{(E-E_{F})}/kT}
  • F(E)=\frac{1}{1-e^{(E-E_{F})}/kT}

Answer: F(E)=\frac{1}{1+e^{(E-E_{F})}/kT}

Q.23. For high conductivity and large temperature coefficient

  • Pure metals are chosen
  • Slightly impure materials are used
  • Alloys are used
  • Super-conductors are used

Answer: Pure metals are chosen

Q.24. The potential barrier at a pn junction is established due to the charge on either side of the Junction. These charges are

  • majority carriers
  • minority carriers
  • both a and b
  • donor and acceptor ions

Answer: donor and acceptor ions

Q.25. In a PN junction, holes diffuse from the p-region to the n-region because

  • they move across the junction by the potential diffierence
  • free electron available in the n-region attract them
  • the holes concentration in the p-region is greater as compared to n-region
  • all of these

Answer: the holes concentration in the p-region is greater as compared to n-region

Q.26. In a crystal diode, the barrier potential offers opposition to only

  • free electrons in n-region
  • holes in p-region
  • majority carriers in both regions
  • minority carriers in both regions

Answer: majority carriers in both regions

Q.27. When a reverse bias is applied to a crystal diode, it

  • raises the potential barrier
  • lowers the potential barrier
  • increases the majority-carrier current greatly
  • none of these

Answer: raises the potential barrier

Q.28. At reverse bias, the number of minority carriers crossing the junction of a diode depends primarily on the

  • concentration of doping impurities
  • rate of thermal generation of electron-hole pairs
  • magnitude of the potential barriers
  • all of these

Answer: all of these

Q.29. When a forward bias is applied to a crystal diode, it

  • raises the potential barrier
  • lowers the potential barrier
  • reduces the majority-carrier current to zero
  • none of these

Answer: lowers the potential barrier

Q.30. Avalanche breakdown in a crystal diode occurs when

  • the potential barrier is reduced to a zero
  • forward current exceeds a certain value
  • reverse bias exceeds a certain value
  • all of these

Answer: reverse bias exceeds a certain value

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