Write the difference between intrinsic and extrinsic semiconductors.

For an intrinsic semiconductor,where $n_{h}$ and $n_{e}$ are the number of holes per unit volume and the number of electrons per unit volume respectively,which of the following relations holds true?

The density of an electron-hole pair in a pure germanium is $3 \times 10^{16} \ m^{-3}$ at room temperature. On doping with aluminium,the hole density increases to $4.5 \times 10^{22} \ m^{-3}$. Now,the electron density (in $m^{-3}$) in doped germanium is:

In a $P$-type semiconductor,the acceptor energy levels $E_A$ are located:

$A$ 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 $\text{cm}^3$.

When the conductivity of a semiconductor is only due to the breaking of covalent bonds,the semiconductor is called: