EXAMPLE $7\mathrm{.}8.$ The electron and hole mobilities of Si sample are $0\mathrm{.}135$ and $0\mathrm{.}048m^2\frac{V}{s}$ respectively. Determine the conductivity of intrinsic Si at $300$ K if the intrinsic carrier concentration is $1\mathrm{.}5{10}^{16}$ atom $\frac{?}{m^3}.$ The sample is then doped with ${10}^{23}$ atoms $\frac{?}{m^3}$ of phosphorus. Determine the equilibrium hole concentration, conductivity and position of the Fermi level relative to the intrinsic lemel