Concept:When a pure tetravalent semiconductor (such as silicon or germanium) is doped with a trivalent impurity (group III element), each dopant atom introduces a vacancy in the valence band known as a hole, making holes the majority charge carriers.
Formula:$$p_h \gg n_e$$
Solution:- Trivalent dopants (e.g., \(\text{B}\), \(\text{Al}\), \(\text{Ga}\), \(\text{In}\)) create an abundance of electron vacancies (holes).
- In p-type material, hole concentration (\(p_h\)) far exceeds the thermally generated electron concentration (\(n_e\)).
- Therefore, holes dominate electrical conduction.
Why other options are incorrect:- Option A: Conduction electrons are minority carriers in p-type semiconductors.
- Option C: Donor ions are created in n-type semiconductors by pentavalent impurities.
- Option D: Acceptor ions are fixed in the crystal lattice and cannot move to carry current.
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