Which one of the following elements, when present as an impurity in silicon makes it a p-type semiconductor?
Which one of the following elements, when present as an impurity in silicon makes it a p-type semiconductor?
$\mathrm{As}$
$\mathrm{P}$
$\mathrm{In}$
$\mathrm{Sb}$
Solution
When silicon is doped with such an impurity valency of which is less than $4, p$-type semiconductor is obtained.
valency of As, P and Sb is +5 and of In is +3 .
Thus, In is the impurity which when added to $\mathrm{Si}$ gives $p$-type semiconductor.