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GATE 2019 EC – Question 20

Electronic Devices · P-N Junction and Semiconductor Devices · 1 mark · Multiple choice

The figure shows the high-frequency C-V curve of a MOS capacitor (at T = 300 K) with $\Phi_{ms}=0$ V and no oxide charges. The flat-band, inversion, and accumulation conditions are represented, respectively, by the points

Diagram for GATE 2019 EC question 20
  1. P, Q, R
  2. Q, R, P
  3. R, P, Q
  4. Q, P, R

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Show answer and explanation

Correct answer: (B) Q, R, P

Explanation

For a $p$-type substrate, a negative gate voltage gives accumulation (high capacitance, point P), $V_G=0$ is the flat-band condition (point Q, since $\Phi_{ms}=0$ and there are no oxide charges) and large positive $V_G$ gives inversion with the low high-frequency capacitance (point R). So the order is Q, R, P.