In $n$-type semiconductor,electrons are majority charge carriers,but it does not show any negative charge. The reason is:

Indium impurity in germanium makes

Explain $n$-type and $p$-type semiconductors based on energy band theory.

In a semiconductor,the number density of intrinsic charge carriers at $27^{\circ} \text{C}$ is $1.5 \times 10^{16} \, \text{m}^{-3}$. If the semiconductor is doped with impurity atoms,the hole density increases to $4.5 \times 10^{22} \, \text{m}^{-3}$. The electron density in the doped semiconductor is $..... \times 10^{9} \, \text{m}^{-3}$.

In a $P$-type semiconductor, the acceptor level is $57 \, meV$ above the valence band. What is the wavelength of light in $\mathring{A}$ required to create a hole? (Given: $h = 6.6 \times 10^{-34} \, J \cdot s$, $c = 3 \times 10^8 \, m/s$, $1 \, eV = 1.6 \times 10^{-19} \, J$)

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 $\text{atoms}/\text{cm}^3$.