In a $P$-type semiconductor, the acceptor level is $57 \text{ meV}$ above the valence band. What is the maximum wavelength of light (in $\mathring{A}$) required to create a hole?

Pure Silicon crystal at $300 \ K$ has equal electron and hole concentration of $1.5 \times 10^{16} \ m^{-3}$. Doping by indium increases $n_h = 4.5 \times 10^{22} \ m^{-3}$. The $n_e$ in the doped silicon is:

In extrinsic $P$ and $N$-type semiconductor materials,the ratio of the impurity atoms to the pure semiconductor atoms is about

If $N_A$ is the number density of acceptor atoms added and $N_D$ is the number density of donor atoms added to a semiconductor,and $n_e$ and $n_h$ are the number density of electrons and holes in it,then:

At a temperature of $500 \ K$,the intrinsic electron number density $(n_e)$ and hole number density $(n_h)$ in a pure semiconductor are equal to $1.5 \times 10^{16} \ m^{-3}$. Now,by adding indium impurity,the hole density $(n_h)$ increases to $4.5 \times 10^{22} \ m^{-3}$. This doped semiconductor is:

$A$ semiconductor doped with a donor impurity is