A p-type semiconductor can be obtained by doping of:

The correct answer is Option (2) → Indium to pure silicon

A p-type semiconductor is made by doping silicon or germanium (group 14, four valence electrons) with a trivalent impurity. Each impurity atom forms only three bonds and leaves a hole, which is the majority carrier. A pentavalent impurity gives an extra electron and makes an n-type semiconductor instead.

NCERT (2026-27):
Extrinsic Semiconductor – “… (i) Pentavalent (valency 5); like Arsenic (As), Antimony (Sb), Phosphorous (P), etc.”

Extrinsic Semiconductor – “… (ii) Trivalent (valency 3); like Indium (In), Boron (B), Aluminium (Al), etc.”

p-type Semiconductor – “This is obtained when Si or Ge is doped with a trivalent impurity like Al, B, In, etc.”

p-type Semiconductor – “… Therefore, extrinsic semiconductors doped with trivalent impurity are called p-type semiconductors.”