Concept:In an N-type semiconductor, donor doping increases the free electron concentration well above the intrinsic level, which simultaneously suppresses the hole concentration via recombination.
Formula:$$n_n p_n = n_i^2 \implies n_n \approx N_D, \quad p_n = \frac{n_i^2}{N_D} \ll n_n$$
Solution:- Donor impurities donate conduction electrons, making electrons the majority charge carriers (\( n_n \approx N_D \)).
- Thermal generation produces a small number of electron-hole pairs, providing a low concentration of minority holes (\( p_n \)).
- Therefore, electrons are majority carriers and holes are minority carriers.
Why other options are incorrect:- Option A: Holes are majority carriers in P-type semiconductors, not N-type.
- Option B: Equal electron and hole concentrations (\( n = p = n_i \)) occur in pure intrinsic semiconductors.
- Option C: Ions are fixed in the crystal lattice and do not serve as mobile charge carriers.
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