If $N_h$ and $N_e$ are the numbers of holes and conduction electrons in an extrinsic semiconductor,respectively,then:

Write the difference between intrinsic and extrinsic semiconductors.

When arsenic is added as an impurity to silicon,the resulting material is

In pure $Si$ at $300 \ K$,the concentration of electrons $(n_e)$ and holes $(n_h)$ is equal and is $1.5 \times 10^{16} \ m^{-3}$. If the concentration of holes $(n_h)$ increases to $3 \times 10^{22} \ m^{-3}$ after doping with Indium,calculate the concentration of electrons $(n_e)$ in the doped $Si$.

$A$ silicon sample is made into a $p$-type semiconductor by doping. Indium atoms are added at a rate of one atom per $5 \times 10^7$ silicon atoms. If the number density of silicon is $5 \times 10^{28} \text{ atoms/m}^3$,calculate the number density of acceptor atoms per $\text{cm}^3$.

What is the valency of donor impurity? Name these impurities.