Question

Why the electron density in the semiconductor increases when increasing of temperature but why not in the case of conductor?

Answer 1

Semiconductors are made up of electon-hole
pairs. At room temperature majority of them
are not allowed to move freely
When temperature increases electron-hole
pair breaks due to which electrons become
free and electron density increases.

In metals,free electrons are available at room
tempetature.When temperature is increased
electron collides with metal atoms more frequently bcoz of which conduction decreases