Question

How does electrical conductivity of a semiconductor change with tem​

Answer 1

Answer:

conductors (e.g Metals) the conduction band is already full with electrons while in semiconductors it is not (most of such materials have bandgap ~ 1-2 eV).

So this explains the behavior in the room temperature. Let’s increase the temperate now, OK?

In semiconductors we will get more electron in the conduction band - the increase in the temperature “allows” them to overcome the bandgap barrier. Hence we will have more electron in the conduction band - but still the total number of electrons will be order of magnitude less compared to metals.

In conductors we already have enough electrons in the conduction band. Now that the temperature is rises the electrons move more sporadically (again due to energy increase) - and this create scattering. You can read more here - Ballistic conduction.