A p-type semiconductor can be obtained by adding
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → aluminum to pure silicon
A p-type semiconductor is made by doping a tetravalent semiconductor (silicon or germanium) with a trivalent impurity. Aluminium has three valence electrons, so it leaves a vacancy (hole) in one bond with the silicon neighbours.
Why the other options are incorrect
Option (1) arsenic to pure silicon — Incorrect. Arsenic is pentavalent; it gives an extra electron and makes an n-type semiconductor.
Option (3) phosphorous to pure germanium — Incorrect. Phosphorus is pentavalent, so germanium doped with it is n-type.
Option (4) antimony to pure carbon — Incorrect. Antimony is pentavalent, so it would donate electrons (n-type), not create holes.
NCERT (2026-27):
Extrinsic Semiconductor – “… This is obtained when Si or Ge is doped with a trivalent impurity like Al, B, In, etc. … Therefore, extrinsic semiconductors doped with trivalent impurity are called p-type semiconductors.”