In a n type semiconductor, the donor energy level is:

The correct answer is Option (4) → just below the conduction band

An n-type semiconductor is made by doping a pentavalent atom (P, As, Sb) into Si or Ge. Four of its five valence electrons form bonds; the fifth is only loosely held, so it needs very little energy to be set free. The energy level of this extra electron, the donor level, therefore lies just below the bottom of the conduction band (about 0.01 eV below it in Ge and 0.05 eV in Si).

Why the other options are incorrect

• Option (1) at the mid point of the energy gap — Incorrect. The middle of the gap is where the Fermi level of an intrinsic semiconductor lies; a donor level at the mid-gap would need a large energy to ionise.

• Option (2) inside the conduction band — Incorrect. The donor level is a localised level in the forbidden gap, not part of the conduction band.

• Option (3) just above the valence band — Incorrect. This is where the acceptor level of a p-type semiconductor lies.

NCERT (2026-27):
Extrinsic Semiconductor – “… In the energy band diagram of n-type Si semiconductor, the donor energy level E_D is slightly below the bottom E_C of the conduction band and electrons from this level move into the conduction band with very small supply of energy.”