When a small amount of impurity atoms are added to semiconductor, then generally its resistivity

Step-by-step solution

When a small amount of Impurity atoms are added to a semiconductor, then generally its resistivity decreases. Explanation: The conductivity of a semiconductor is given by = n _ e e _ e + n _ h e _ h where n_e and n_h= number of electrons and holes per unit volume and _ e and _ h = mobility of electrons and holes. When impurity atoms are added in a semiconductor, then the concentration of holes and electrons increases. So, the conductivity Increases and hence the resistivity ( = 1 ) of semiconductors decreases.