(i) In n-type semiconductor, the semiconductor is doped with pentavalent impurity. The electrons are majority carriers and holes are minority carriers
In energy band diagram of n-type semiconductor, the donor energy level is slightly below the bottom of conduction band and thus, the electron can move to conduction band, even with small supply of energy.
In p-type semiconductor, the semiconductor is doped with trivalent impurity. The holes are the majority carriers and electrons are the minority carriers. In energy band diagram of p-type, the acceptor energy level is slightly above the top of valence band .
Thus, even with small supply of energy, electron from valence band can jump to level and ionise the acceptor, negatively.