How electron -hole pairs are created in a semiconductor material ?

Explanation

(i) A small increase in temperature is sufficient enough to break some of the covalent bonds and release the electrons free form the lattice.
(ii) As a result, some states in the valence band become empty and the same number of states in the conduction band will be occupied.
(iii) The vacancies produced in the valence band are called holes. As the holes are deficiency of electrons , they are treated to possess positive charges . Hence, electrons and holes are the two charge carriers in semiconductors.