Concept:In an intrinsic semiconductor, current is carried by both free electrons moving through the conduction band and holes moving through the valence band.
Formula:$$J_{\text{total}} = J_n + J_p = q n \mu_n E + q p \mu_p E = q n_i (\mu_n + \mu_p) E$$
Solution:- Conduction electrons move opposite to the applied electric field in the conduction band.
- Valence holes move in the direction of the applied electric field in the valence band.
- Because their charges and directions of motion are both opposite, both carrier types contribute positively to the total conventional current.
Why other options are incorrect:- Option B: Holes exist in the valence band, not the conduction band.
- Option C: Conduction band electrons carry significant current alongside valence holes.
- Option D: Protons are bound in atomic nuclei and do not conduct current.
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