Silicon is a semiconductor. If a small amount of $As$ is added to it,then its electrical conductivity . . . . . . .

What is the number density of donor atoms which must be added to a pure germanium semiconductor to make an $n$-type semiconductor of conductivity $6.4 \ \Omega^{-1} \ cm^{-1}$? The mobility of electrons in $n$-type germanium is $4 \times 10^3 \ cm^2 \ V^{-1} \ s^{-1}$. Neglect the contribution of holes to conductivity.

If ${n_e}$ and ${n_h}$ are the number of electrons and holes in a semiconductor heavily doped with phosphorus,then

If one indium atom is doped per $5 \times 10^7$ silicon atoms,and the number density of silicon atoms is $5 \times 10^{28} \, \text{atoms}/\text{m}^3$,find the number density of acceptor atoms in $\text{atoms}/\text{cm}^3$.

In which of the following statements is the obtained impure semiconductor of $p$-type?

What is the conductivity of a pure silicon crystal at $300 \ K$? The number of electron-hole pairs per $cm^3$ is $1.072 \times 10^{10}$. Given $\mu_n = 1350 \ cm^2/V \cdot s$ and $\mu_p = 480 \ cm^2/V \cdot s$.