Question

If $N_P$ and $N_e$ be the numbers of holes and conduction electrons in an extrinsic semiconductor, then,

• A. $N_P$ > $N_e$
• B. $N_P$ =$N_e$
• C. $N_P$ < $N_e$
• D. $N_P$ > $N_e$ or $N_P$ < $N_e$ depending on the nature of impurity

Answer 1

The correct option is D $N_P$ > $N_e$ or $N_P$ < $N_e$ depending on the nature of impurity

When a pure semiconductor is doped with a trivalent impurity, we get a $P-$type semiconductor in which, $N_P>N_e$

Similarly, When a pure semiconductor is doped with a pentavalent impurity, we get a $N-$type semiconductor in which, $N_e>N_P$.

So, whether $N_P>N_e$ or $N_e>N_P$, it depends upon the nature of the impurity.

Hence, $\left(D\right)$ is the correct answer.