In the energy band diagram of a material shown below,the open circles and filled circles denote holes and electrons respectively. The material 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:

Consider an $n$-type semiconductor in which $n_e$ and $n_h$ are the number of electrons and holes,respectively.
$(A)$ Holes are minority carriers.
$(B)$ The dopant is a pentavalent atom.
$(C)$ $n_e n_h \neq n_i^2$ (where $n_i$ is the number of electrons or holes in the semiconductor when it is in its intrinsic form).
$(D)$ $n_e n_h \geq n_i^2$.
$(E)$ The holes are not generated due to the donors.
Choose the correct answer from the options given below.

The net charge on an $N-$type semiconductor is

Which impurity is doped in $Si$ to form an $N$-type semiconductor?

If $n_{e}$ and $n_{h}$ are the number of electrons and number of holes respectively in a semiconductor heavily doped with phosphorus,then: