Question

Why does the conductivity of a semiconductor increase with increased temperature, but a metal’s conductivity decreases?

Answer 1

Ans :

The conductivity of semiconductor increase with increase in temperature because as the temperature is increased , the electrons jump from valence band to conduction band , which causes dwindling of resistance and hence the conductance increases.

Now when the temperature of the metal is increased , the collisions of electrons increase due to increase in the thermal energy. This disrupts the flow of electrons that is required for the conductance. So the increase in temperature decreases the conductivity of the metal.