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Chemical Engineering Basics - Engineering

Q1:

With increase in temperature, the electrical conductivity of semiconductors

A increases

B decreases.

C remain constant.

D either (a) or (b), depends on the type of semi-conductor.

ANS:A - increases

With an increase in temperature, the electrical conductivity of semiconductors increases. Intrinsic semiconductors:

  • With increasing temperature, more electrons gain sufficient thermal energy to move from the valence band to the conduction band, creating more charge carriers (electrons and holes). This results in an increase in electrical conductivity.
Extrinsic (doped) semiconductors:
  • For n-type semiconductors (doped with donor impurities), the number of free electrons increases with temperature due to thermal excitation, leading to increased conductivity.
  • For p-type semiconductors (doped with acceptor impurities), the number of holes increases with temperature due to thermal excitation, also resulting in increased conductivity.
Therefore, the correct statement is: increases.