When arsenic is added as an impurity to silicon,the resulting material is

Germanium $(Ge)$ is doped with Aluminum $(Al)$. If the concentration of acceptor atoms is $N_A \cong 10^{21} \text{ atoms/m}^3$ and the intrinsic carrier concentration is $n_i = 10^{19} \text{ m}^{-3}$,then the concentration of electrons is:

$A$ $P$-type semiconductor is .......

If $n_{e}$ and $n_{h}$ are the number of electrons and number of holes respectively in a semiconductor heavily doped with phosphorus,then:

In $N$-type semiconductors,the majority charge carriers are

If the ratio of electron and hole currents in a semiconductor is $\frac{7}{4}$ and the ratio of drift velocities of electrons and holes is $\frac{5}{4}$, then the ratio of concentrations of electrons and holes will be