GATE EC 2018 Set 1 — Question 17
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Electronic Devices → Carrier Transport → Diffusion & Drift Current
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Question
In a p-n junction diode at equilibrium, which one of the following statements is NOT TRUE?
Correct answer
(D) On an average, electrons drift and diffuse in the same direction.
Solution
In a p-n junction diode at equilibrium, the net current for each carrier type (electrons and holes) must be zero. This means that for each carrier, the drift current and diffusion current must be equal in magnitude and opposite in direction.For electrons: .
Thus, on average, electrons drift and diffuse in opposite directions. Statement (D) claims they are in the same direction, which is NOT TRUE.Regarding other statements:
(A) Hole diffusion is
(B) Hole drift is
(C) Holes drift
Thus, on average, electrons drift and diffuse in opposite directions. Statement (D) claims they are in the same direction, which is NOT TRUE.Regarding other statements:
(A) Hole diffusion is
P → N, electron diffusion is N → P (electron current is P → N). Both are in the same direction. (TRUE)(B) Hole drift is
N → P, electron drift is P → N (electron current is N → P). Both are in the same direction. (TRUE)(C) Holes drift
N → P and electrons drift P → N, which are opposite directions. (TRUE)Continue learning with Success Tracker
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