Question

Assertion (A): The conductivity of an n-type semiconductor is higher than that of a p-type semiconductor at a given temperature.

Reason (R): The electrons being in the conduction band in n-type semiconductor are more mobile than the holes in the valence band in p-type semiconductor.

पर्याय

• Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).

• Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of the Assertion (A).

• Assertion (A) is true, but Reason (R) is false.

• Both Assertion (A) and Reason (R) are false.

Answer 1

Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).

Explanation:

Conductivity in semiconductors depends on the concentration of charge carriers and their mobility

Conductivity σ = e(n_eµ_e + n_hµ_h)

Where n is the concentration and µ is the mobility.

The assertion (A) is true. N-type semiconductors, in which electrons make up the majority of the carriers, often have higher conductivity than p-type semiconductors, in which holes make up the majority of the carriers, at the same temperature and doping levels.

Mobility (µ) is the drift velocity per unit electric field, hence the reason (R) is true. In the conduction band, where they are comparatively free, electrons travel. The slower process of bound electrons leaping into empty sites is how holes travel in the valence band. Therefore, µ_e > µ_h.

Since µ_e > µ_h, for the same carrier concentration, the conductivity σ ≈ n_eµ will be higher for n-type than for p-type.