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?

$A$ $P$-type semiconductor 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:

Write the difference between intrinsic and extrinsic semiconductors.

Which type of impurity is to be added to a pure semiconductor to get a $p$-type semiconductor?

Pure $Si$ at $500\, K$ has equal number of electron $(n_e)$ and hole $(n_h)$ concentrations of $1.5 \times 10^{16}\, m^{-3}$. Doping by indium increases $n_h$ to $4.5 \times 10^{22}\, m^{-3}$. The doped semiconductor is of