Why does the electrical conductivity of semi-conductors increase with rise in temperature ?

Explanation

The electrical conductivity of a metal decreases with the rise in temperature because the positively charged kernels present in the electron sea also acquire mobility and obstruct the movement of valence electrons responsible for conductivity. In semi-conductros, the electrical conductivity increases because more electrons are in a position to move from valence band to the conduction band since there is only a small energy gap.