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The conductivity of a semiconductor increases with increase in temperature because
CBSE | Class 12 | Guides | NCERT Exemplar | Physics | Semiconductor Electronics: Materials, Devices and Simple Circuits
The conductivity of a semiconductor increases with increase in temperature because

 (a) number density of free current carriers increases

(b) relaxation time increases

(c) both number density of carriers and relaxation time increase

(d) number density of current carriers increases, relaxation time decreases but the effect of a decrease in relaxation time is much less than the increase in number density

Answer:

The correct option is (a) number density of free current carriers increases

Explanation:

Because the density of charge carriers (electron holes) in semiconductors is very low, the resistance is high. The density of charge carriers (density) increases as temperature rises, increasing conductivity. The speed of free electrons increases as the temperature of the semiconductor rises, reducing the relaxation time. Because the charge carrier density is low, the influence on relaxation time is minimal.

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