GATE 2016 EC (EC3) – Question 21
The figure shows the band diagram of a metal–oxide–semiconductor structure. Its surface region is in
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Correct answer: (A) inversion
Explanation
In the semiconductor bulk, the Fermi level lies above the intrinsic level, indicating n-type material. Toward the oxide interface the bands bend upward.
At the surface the intrinsic level lies above the Fermi level, so holes dominate there even though electrons dominate in the bulk. This change of majority carrier type is **inversion, A**. Mere depletion would not reverse the majority carrier type.