Semiconductors & p–n Junctions — A/L Physics

How do I practise Semiconductors & p–n Junctions?

1 question with a worked solution

1. What type of extrinsic semiconductor is produced when an intrinsic crystalline silicon wafer (Group IV) is doped with trivalent impurity atoms such as Indium or Boron (Group III)?
   1. A) p-type semiconductor with holes as majority charge carriers
   2. B) n-type semiconductor with conduction electrons as majority charge carriers
   3. C) Intrinsic semiconductor with zero electrical conductivity
   4. D) Superconducting ceramic compound
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   Correct answer: A) p-type semiconductor with holes as majority charge carriers

   Doping silicon with Group III elements creates acceptor energy levels just above the valence band. Each trivalent atom shares 3 valence electrons, leaving one unfilled covalent bond—a hole. Hence, holes become the majority charge carriers, yielding a p-type semiconductor.

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   Step 1: Group IV doped with Group III (acceptor) -> excess mobile holes. Step 2: Holes are majority carriers -> p-type semiconductor. Answer: p-type semiconductor with holes as majority charge carriers.
   Modelled on: the A/L Physics examination pattern

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Where does Semiconductors & p–n Junctions fit in the syllabus?

Unit 9.1 · Year 2 · Term 2