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At room temperature, in an intrinsic (pure) semiconductor, which charge carriers are responsible for electrical conduction?

Difficulty: Easy

Correct Answer: holes and electrons

Explanation:


Introduction / Context:
Intrinsic semiconductors (e.g., undoped silicon) exhibit thermally generated carriers even without intentional doping. Recognizing that both electron and hole populations participate in conduction is foundational for understanding conductivity, intrinsic carrier concentration, and the effect of temperature on devices.


Given Data / Assumptions:

  • Intrinsic semiconductor with bandgap Eg.
  • At room temperature, thermal energy produces electron–hole pairs (EHPs).
  • Carrier concentrations are equal: n = p = ni.


Concept / Approach:
Every thermally generated electron in the conduction band leaves behind a hole in the valence band. Thus, intrinsic conduction is a combination of electron drift/diffusion and hole drift/diffusion. Conductivity is σ = q(n μn + p μp) = q ni (μn + μp). Both carrier types contribute concurrently to current flow under an applied electric field.


Step-by-Step Solution:

Recognize that generation creates paired carriers: electrons and holes.Use intrinsic condition: n = p = ni; both terms appear in σ.Therefore, total current has components from both electrons and holes.


Verification / Alternative check:

If the material were doped (n-type or p-type), majority carriers dominate, but in the intrinsic case the symmetry between n and p confirms the answer.


Why Other Options Are Wrong:

Holes only or electrons only ignores the paired nature of intrinsic generation.Ions/excitons: not the principal current carriers in standard intrinsic conduction under bias.


Common Pitfalls:

Assuming one carrier dominates because μn > μp; although mobilities differ, both carrier densities are equal and both contribute.


Final Answer:

holes and electrons
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