An n-type and a p-type semiconductor can be obtained by doping pure germanium (Ge) with
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → Arsenic and Boron, respectively
Germanium is tetravalent. A pentavalent impurity (P, As, Sb) gives an extra electron and makes an n-type semiconductor; a trivalent impurity (B, Al, Ga, In) leaves a hole and makes a p-type semiconductor. Arsenic is pentavalent and boron is trivalent.
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.”