In order to fabricate n-type semiconductor, the impurity elements used are
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → donor atoms like Phosphorus, Arsenic.
An n-type semiconductor is made by doping Si or Ge with a pentavalent (donor) impurity. Four of its five valence electrons form covalent bonds; the fifth is loosely bound and is easily freed, so electrons become the majority carriers.
Option (1) acceptor atoms like Aluminum, Indium. — Incorrect. Aluminium and indium are trivalent acceptors; they create holes and give a p-type semiconductor.
Option (2) donor atoms like Phosphorus, Arsenic. — Correct. Phosphorus and arsenic are pentavalent and donate an extra electron each.
Option (3) carbon as it has four valence electrons. — Incorrect. Carbon is tetravalent like silicon; it adds no free electron.
Option (4) semiconductor atoms like Silicon and Germanium. — Incorrect. Silicon and germanium are the host (intrinsic) material, not the impurity.
NCERT (2026-27):
Summary – “… n-type semiconducting Si or Ge is obtained by doping with pentavalent atoms (donors) like As, Sb, P, etc., while p-type Si or Ge can be obtained by doping with trivalent atom (acceptors) like B, Al, In etc.”