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⚛️ Physics  ·  Semiconductor Electronics  ·  NEET & JEE

The threshold voltage of a MOSFET is the gate voltage at which:

Answer: Inversion layer forms (channel becomes conducting).

  • A Significant gate leakage current begins to flow through the oxide
  • B Inversion layer forms (channel becomes conducting)
  • C The drain current becomes equal to the supply current
  • D The source and drain terminals become directly shorted together

Correct answer: B. Inversion layer forms (channel becomes conducting)

Explanation: Threshold voltage Vth: minimum gate-source voltage to create conducting channel (inversion layer) between source and drain.

Conductorconduction bandvalence bandbands overlapSemiconductorconduction bandvalence bandsmall gap (~1 eV)Insulatorconduction bandvalence bandlarge gap(> 3 eV)

Conductors have overlapping bands, semiconductors have a small energy gap that can be bridged by heat or doping, and insulators have a large gap that blocks conduction.

Concept context

Band theory, p-n junction, diodes, transistors, logic gates, and integrated circuits.

Read the full Semiconductor Electronics notes →