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⚛️ Physics  ·  Semiconductor Electronics  ·  NEET & JEE

The built-in potential (contact potential) across a p-n junction:

Answer: Cannot be utilized as a battery (thermal equilibrium).

  • A Can be measured with voltmeter directly overall
  • B Cannot be utilized as a battery (thermal equilibrium)
  • C Decreases with doping in most cases under typical conditions
  • D Is zero at room temperature according to standard textbooks

Correct answer: B. Cannot be utilized as a battery (thermal equilibrium)

Explanation: Built-in potential (0.6-0.7V for Si): thermodynamic equilibrium quantity. Cannot be used as voltage source; no net current in equilibrium.

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 →