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Question 20210
JEE Physics · Medium

Semiconductors: Donor and Acceptor Levels MCQ

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Donor and Acceptor LevelsMediumQuestion 20210

Question

Donor energy levels are located:
  1. A
    In the middle of the energy gap
  2. B
    Just below the conduction band
    Correct
  3. C
    Just above the valence band
  4. D
    Above the conduction band

Correct answer

Just below the conduction band

Explanation

Donor levels from pentavalent impurities sit very close to the conduction band (Ei_donor ≈ 0.01–0.05 eV below CB in Si). Room temperature thermal energy easily ionises them → free electrons in the CB. Acceptor levels from trivalent impurities sit just above the valence band.

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