When a pure semiconductor is heated, its resistance
  • Goes down.
  • Goes up.
  • Remains the same.
  • None of the above.
What is the order of forbidden gap in the energy bands of silicon?
  • 3.1 eV
  • 0.1 eV
  • 2.1 eV
  • 1.1 eV
The densities of electrons and holes in an extrinsic semiconductor are 8 x 1015 cm-3 and 5 x 1012 cm-3 respectively. The mobilities of electrons and holes are respectively 23 x 103 cm3 / Vs and 102 cm3 / Vs. Which type of semiconductor is it?
  • p-type only
  • n-type only
  • either n or p type
  • both n and p type
A semiconductor is formed by
  • Covalent bonds
  • Electrovalent bonds
  • Coordinate bonds
  • None of above
Arrange the materials in ascending order of energy band gaps
  • conductor, semiconductor, insulator
  • insulator, semiconductor, conductor
  • semiconductor, conductor, insulator
  • insulator, conductor, semiconductor
In a semiconductor, current conduction is due
  • Only to holes.
  • Only to electrons
  • To holes and electrons
  • None of the above
Electrons moving like molecules of a gas exist in:
  • all solids
  • covalent solids
  • metallic solids
  • ionic solids
An n-type semiconductor is
  • Not charged at all
  • Positively charged
  • Electrically neutral
  • Negatively charged
Mobilities of electrons and holes in a sample of intrinsic germanium semiconductor at room temperature are 0.36m2/volt-sec and 0.17 m2/volt-sec respectively. If the electron and hole densities are each equal to 2.5 X 1019/m3, the conductivity is.
  • 1.22 S/m
  • 3.12 S/m
  • 4.12 S/m
  • 2.12 S/m
In a semiconductor, the energy gap between valence band and conduction band is about
  • 10 eV
  • 5 eV
  • 1 eV
  • 15 eV
0 h : 0 m : 1 s

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