When a small amount of impurity atoms are added to a semiconductor then generally its resistivity
When a small amount of impurity atoms are added to a semiconductor then generally its resistivity
decreases.
increases.
does not Change.
may increase or decrease depending upon the percentage of doping.
Solution
The conductivity of a semiconductor is given by
\(\sigma=n_{e} e \mu_{e}+n_{h} e \mu_{h}\)
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.
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