Semiconductor Electronic: Material, Devices And Simple Circuits — Physics STD 12 Science — Question

4. Number density of current carriers increases, relaxation time decreases but effect of decrease in relaxation time is much less than increase in number density.

Solution:
With increase in temperature, the number density of current carries increases, relaxation time decreases but effect of decrease in relaxation is much less than increase in number density. So, the conductivity of a semiconductor increases with increase in temperature.