When a small amount of impurity atoms are added to semiconductor, then generally its resistivity
When a small amount of impurity atoms are added to semiconductor, then generally its resistivity
may increase or decrease depending upon the percentage of doping.
increases.
decreases.
does not change.
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
$\sigma=\mathrm{n}_{\mathrm{e}} \mathrm{e} \mu_{\mathrm{e}}+\mathrm{n}_{\mathrm{h}} \mathrm{e} \mu_{\mathrm{h}}$
where $n_e$ and $n_h=$ number of electrons and holes per unit volume
and $\mu_{\mathrm{e}}$ and $\mu_{\mathrm{h}}=$ 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 $\left(\rho=\frac{1}{\sigma}\right)$ of semiconductors decreases.