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

The resistivity of a pure semiconductor is $0.5 \ \Omega m$. If the electron and hole mobility are $0.39 \ m^2 / V-s$ and $0.19 \ m^2 / V-s$ respectively,then calculate the intrinsic carrier concentration.

In a semiconductor,the number densities of electrons and holes are $8 \times 10^{18} \ m^{-3}$ and $5 \times 10^{18} \ m^{-3}$ respectively. If the mobilities of electrons and holes are $2.3 \ m^2/V \cdot s$ and $0.01 \ m^2/V \cdot s$ respectively,then the semiconductor is:

Suppose a pure $Si$ crystal has $5 \times 10^{28}$ atoms $m^{-3}$. It is doped with $1 \text{ ppm}$ concentration of pentavalent $As$. Calculate the number of electrons and holes. $(n_i = 1.5 \times 10^{16} \text{ m}^{-3})$

Which of the following statements is incorrect?

Write briefly on $n$-type and $p$-type semiconductors.