$A$ $P$-type semiconductor is:

The valence of the impurity atom that is to be added to a germanium crystal to make it an $N$-type semiconductor is:

If the ratio of the concentration of electrons to that of holes in a semiconductor is $\frac{7}{5}$ and the ratio of currents is $\frac{7}{4}$,then what is the ratio of their drift velocities?

$A$ $Ge$ specimen is doped with $Al$. The concentration of acceptor atoms is $10^{21} \text{ atoms}/m^3$. Given that the intrinsic concentration of electron-hole pairs is $10^{19} /m^3$, the concentration of electrons in the specimen is:

In an $n-$type semiconductor,which of the following statements is true?

$A$ silicon specimen is made into a $p$-type semiconductor by doping,on an average,one indium atom per $5 \times 10^7$ silicon atoms. If the number density of atoms in the silicon specimen is $5 \times 10^{28} \text{ atoms } m^{-3}$,then the number of acceptor atoms in silicon per cubic centimeter will be: